Idemitsu Kosan : Notice of The 111th Ordinary General Meeting of Shareholders

To Our Shareholders

I would like to express my sincere appreciation for your continued support of our business.

In FY2025, the final year of our previous Medium-term Management Plan, we made further efforts to improve capital efficiency and profitability in our existing businesses, while making steady progress toward achieving carbon neutrality and circular society.

FY2026 marks the launch of a new Medium-term Management Plan with a horizon extending to FY2030. Right now, we are facing a rapidly evolving business landscape, shaped by surging resource prices due to the deteriorating situation in the Middle East, heightened energy security concerns, and a shifting decarbonization timeline. To navigate these growing uncertainties, we will actively pursue three initiatives — exploiting existing businesses, creating growth businesses, and staging up low-carbon/decarbonization businesses — while balancing short- to medium-term profitability with medium- to longterm growth.

Going forward, we will continue to pursue sustainable growth and enhance corporate value, rooted in our founding principle of “People-Centered Management” and embodying our vision of “Your Reliable Partner for a Brighter Future” and “Shaping Change.”

We humbly ask you, our valued shareholders, for your continued support.

Yours very truly, Representative Director and President,

Idemitsu Kosan Co.,Ltd.

Noriaki Sakai

Securities Code: No. 5019

June 2, 2026

To the Shareholders:

NOTICE OF THE 111TH ORDINARY GENERAL MEETING OF SHAREHOLDERS

Dear Shareholders:

We would like to express our appreciation for your continued support.

Please note that the 111th Ordinary General Meeting of Shareholders of the Company will be held as described below.

We are convening this Ordinary General Meeting of Shareholders in accordance with measures to provide information in electronic format, such as information contained in the Reference Documents for the General Meeting of Shareholders, etc. (information to be provided in electronic format), as posted on the Internet websites below. Please access and refer to the relevant websites.

Our website: https://www.idemitsu.com/jp/ir/stock/meeting/index.html (in Japanese) The Tokyo Stock Exchange’s website (TSE Listed Company Information Service): https://www2.jpx.co.jp/tseHpFront/JJK010010Action.do?Show=Show (in Japanese)

(Please access the TSE website above and enter either “出光興産” (Idemitsu Kosan) in the “銘柄名(会社名)” (Issue name (company name)) field or our securities code “5019” in the “コード” (Code) field, and press the “検索” (Search) button. Thereafter, please first select “基本情報” (Basic information) followed by “縦覧書類/PR情報” (Documents for public inspection/PR information). The information can be accessed from the section titled “株主総会招集通知/株主総会資料” (Notice of General Shareholders Meeting /Informational Materials for a General Shareholders Meeting) under “縦覧書類” (Filed information available for public inspection).)

Website at which materials for general meetings of shareholders are available: https://www.soukai-portal.net

If you do not attend the Ordinary General Meeting of Shareholders in person, you may exercise your voting rights either in writing (by post) or via the Internet, etc. Please review the Reference Documents for the General Meeting of Shareholders and exercise your voting rights by 5:00 p.m., Tuesday, June 23, 2026.

Yours very truly,

Noriaki Sakai Representative Director President

Idemitsu Kosan Co.,Ltd. 2-1, Otemachi 1-chome, Chiyoda-ku, Tokyo, Japan

Description

1. Date and hour of the meeting: Wednesday, June 24, 2026, at 10:00 a.m.

2. Place of the meeting: Otemachi Mitsui Hall

   Otemachi One Mitsui Bussan Building 3F

   1. , Otemachi 1-chome, Chiyoda-ku, Tokyo, Japan

3. Matters forming the objects of the meeting: Matters to be reported:

   1. Report on the business report, the consolidated financial statements and the results of audit of the consolidated financial statements by the accounting auditors and the Audit & Supervisory Board for the 111th fiscal year (from April 1, 2025 to March 31, 2026)

   2. Report on the non-consolidated financial statements for the 111th fiscal year (from April 1, 2025 to March 31, 2026)

   Matters to be resolved:

   Proposition No. 1: Election of 13 Directors

   Proposition No. 2: Election of 2 Audit & Supervisory Board Members Proposition No. 3: Revision of the Terms of Performance-Linked Stock

   Compensation, etc. for Directors, etc.

4. Matters regarding exercise of voting rights:

1. If you expect to be present by proxy, please make a document evidencing his/her power of attorney presented to a receptionist at the place of the meeting, together with the voting form. (Such proxy must be another shareholder (being one (1) person) of the Company entitled to vote.)

2. If any institutional investor or any other shareholder who holds shares on behalf of third parties desires to exercise the voting rights in a non-uniform manner, please give notice to that effect and of the reason therefor to the Company no later than three (3) days prior to the date of this Ordinary General Meeting of Shareholders.

3. All fees payable to Internet service providers and telecommunication carriers (such as phone line charges) in accessing the website for the exercise of voting rights must be borne by the shareholders.

• The reception of this meeting will begin at 9:00 a.m. on the date of this Ordinary General Meeting of Shareholders.

• If you exercise your voting rights in writing (by post) and do not indicate your approval or disapproval with respect to any proposition in your voting form, you will be deemed to have indicated your approval.

• If there are any corrections to information provided in electronic format, we will post a notice on the relevant Internet websites set forth in the preceding page, together with the information before and after the correction.

• We will send documents containing information provided in electronic format to the shareholders who request delivery of such documents. Please note that the information listed below is not included in those documents in accordance with the applicable laws and ordinances and Article 15 of the Articles of Incorporation of the Company.

  1. “Assets and income/loss,” “Main businesses,” “Major business offices and plants,” “Other important matters concerning the current state of the Group,” “Accounting auditors,” “Systems to secure the properness of business activities (so-called “internal control systems”) and the summary of the status of the operation of the systems,” and “Fundamental policy on corporate control” of the Business Report

  2. “Consolidated statement of changes in net assets,” and “Notes to consolidated financial statements” of the consolidated financial statements

  3. “Non-consolidated statement of changes in net assets,” and “Notes to non-consolidated financial statements” of the non-consolidated financial statements

As such, the business report, the consolidated financial statements, and the non-consolidated financial statements included in those documents are part of the documents that have been audited by the accounting auditors in preparing their accounting auditors’ report and by the Audit & Supervisory Board Members in preparing their audit report, respectively.

Instructions for Exercising Voting Rights

The following methods are available for voting at the General Meeting of Shareholders. As a measure to allow shareholders who do not attend the meeting physically to participate in the meeting, the Company will (1) provide a live stream of the meeting and (2) accept questions in advance. We ask all shareholders to please make use of them.

1. Voting by Attendance at the General Meeting of Shareholders

   Please present the enclosed voting form to the reception desk if you are present at the meeting. Date and hour of the meeting: Wednesday, June 24, 2026, at 10:00 a.m.

2. Postal Voting

   Please indicate “Approve” or “Disapprove” with respect to each proposition on the voting form and submit the form.

   Votes must be received by: Tuesday, June 23, 2026, 5:00 p.m.

3. Electronic Voting via the Internet, etc.

Please input “Approve” or “Disapprove” in conformance with the guidance on the next page. Voting must be completed by: Tuesday, June 23, 2026, 5:00 p.m.

Please indicate approval or disapproval with respect to each proposition.

Proposition No. 1 and No. 2

Approval of all candidates: Mark ○ in the box labelled “賛” Disapproval of all candidates: Mark ○ in the box labelled “否”

Disapproval of certain candidates: Mark ○ in the box labelled “賛” and indicate the

number of each candidate you wish to disapprove.

Proposition No. 3

Approval: Mark ○ in the box labelled “賛” Disapproval: Mark ○ in the box labelled “否”

If you vote both by post and via the Internet, etc., only the vote exercised via the Internet, etc. will be treated as valid.

If you vote more than once via the Internet, etc., only the most recent vote will be treated as valid.

Deadline for Internet voting: Tuesday, June 23, 2026, 5:00 p.m.

Method of voting by smartphone, etc.

1. Please scan the QR Code® located on the voting form.

   * “QR Code” is a registered trademark of Denso Wave Incorporated.

2. On the top page of 株主総会ポータル® (General Shareholders Meeting Portal), please tap the “議決権行使へ” (exercise voting rights) button.

3. The top page of スマート行使® (Smart Exercise) will be displayed. Please input “Approve” or “Disapprove” in conformance with the instructions on the display.

   Method of voting by PC, etc.

   At the following URL, please input the log-in ID and password stated on the voting form for access. After logging in, please input “Approve” or “Disapprove” in conformance with the instructions on the display.

   株主総会ポータル (General Shareholders Meeting Portal) URL https://www.soukai-portal.net

   The voting website can also be used: https://www.web54.net Information on acceptance of questions in advance

   Deadline for acceptance of questions in advance: Friday, June 12, 2026, 5:00 p.m.

   For this meeting, we will accept questions in advance about our propositions, details of business, etc. from shareholders through the 株主総会ポータル (General Shareholders Meeting Portal). From among the questions that we receive, we will address those that we consider to be of high interest for shareholders at the meeting. Please access the 株主総会 ポータル (General Shareholders Meeting Portal) in the same way as the method of voting described above and tap/click on “事前質問へ” (submit questions in advance) on the top page. Once the “事前質問のご入力” (input questions in advance) screen is displayed, please input questions in conformance with the instructions on the display.

   * Please note that we will not individually answer each question received.

   Notes:

   • If you change your votes after the casting thereof, you need to input the “議決権行 使コード” (voting code) and “パスワード” (password) stated on the voting form.

   • If you vote both via the Internet and by post, only the vote exercised via the Internet will be treated as valid. If you vote more than once via the Internet, only the most recent vote will be treated as valid.

For inquiries:

Sumitomo Mitsui Trust Bank, Limited Stock Transfer Web Support

Phone No. 0120-652-031 (9:00 a.m. to 9:00 p.m.) (JST)

Institutional investors may use the electronic voting platform for institutional investors operated by ICJ, Inc.

Reference Documents for the General Meeting of Shareholders

Proposition No. 1: Election of 13 Directors

The term of office of all the Directors will expire at the close of this Ordinary General Meeting of Shareholders. Hence, it is hereby proposed that 13 Directors be elected.

The candidates for Director are as follows:

Head of Safety & Environmental

* Ratio of Outside Directors: 38%

(Important

concurrent office)

Representative Director

and President, Nissho Kosan Co., Ltd.

Representative Director and President, Showa Kosan Co., Ltd.

Representative Director and President, ZEN Co., Ltd.

Representative Director

and President, ENN Co., Ltd.

* Mr. Suzuki serves as an Executive Member of the Policy Board of the Japan Business Federation (“Keidanren”), and the Company has transactions with this organization, including annual membership fees.

However, the transaction amount for FY2025 was approximately ¥25 million, which accounts for less than 2% of the Company’s consolidated net sales. Also, Mr. Suzuki serves as Vice Chairman and Executive Director of the Japan Association of Corporate Executives (KEIZAI DOYUKAI), and the Company has transactions with this organization, including membership fees. However, the transaction amount for FY2025 was approximately

¥0.6 million, which amounts to a negligible proportion of our consolidated sales. While the Company incurs entertainment expenses with Teijin Limited, the amount is negligible, totaling less than ¥100,000 for FY2025.

(Notes) 1. Mr. Shunichi Kito serves as the President of the Petroleum Association of Japan, and the Company engages in transactions with said Association such as the payment of membership fees.

1. Mr. Masakazu Idemitsu serves as Representative Director and President of Nissho Kosan Co., Ltd., Showa Kosan Co., Ltd., ZEN Co., Ltd., and ENN Co., Ltd., who are major shareholders of the Company. The Company engages in transactions with Nissho Kosan involving real estate rental fees and electricity charges, and with Showa Kosan involving real estate rental fees. Mr. Idemitsu also serves as Representative Director of General Incorporated Association Idemitsu Kosan Corporate History and Philosophy Laboratory, and the Company engages in outsourcing transactions with said Laboratory.

2. There is no special relationship between any candidate for Director and the Company, except for Mr. Shunichi Kito and Mr. Masakazu Idemitsu.

3. Mr. Jun Suzuki, Ms. Shiori Nagata, Ms. Mio Kashiwamura, Ms. Sumiko Takeuchi, and Mr. So Hirano are candidates for Outside Director.

4. Under Article 427, Paragraph 1 of the Companies Act of Japan, the Company has entered into agreements with Mr. Masakazu Idemitsu, Mr. Kazunari Kubohara, Mr. Jun Suzuki, Ms. Shiori Nagata, and Ms. Mio Kashiwamura, respectively, to limit the liability for damages provided for in Article 423, Paragraph 1 of the Companies Act of Japan. Under the agreement, the liability is limited to the amount provided for under law. If the reelection of Mr. Masakazu Idemitsu, Mr. Kazunari Kubohara, Mr. Jun Suzuki, Ms. Shiori Nagata, and Ms. Mio Kashiwamura is approved, the Company plans to continue the respective agreements. In addition, if Ms. Sumiko Takeuchi and Mr. So Hirano are elected, the Company plans to enter into the same agreement with each of them to limit the liability for damages.

5. The Company has entered into a liability insurance contract for Directors and Audit & Supervisory Board Members with an insurance company pursuant to Article 430-3, Paragraph 1 of the Companies Act of Japan. Under said insurance contract, the insurance company shall compensate for damages that may result from the insured persons (including the Directors of the Company) assuming responsibility in connection with the execution of their duties or receiving claims related to the pursuit of such responsibility. In the event that each candidate is elected and assumes office as a Director of the Company, he/she will be insured under said insurance contract. Said insurance contract will be renewed with the same contents upon the next renewal.

6. The Company has registered Mr. Jun Suzuki, Ms. Shiori Nagata, and Ms. Mio Kashiwamura as independent officers with the Tokyo Stock Exchange in accordance with its rules. In addition, Ms. Sumiko Takeuchi and Mr. So Hirano satisfy the requirements for independent officers set by the Tokyo Stock Exchange, and the Company plans to register them as independent officers with the Tokyo Stock Exchange.

7. The number of shares of the Company held by each candidate for Director includes the candidate’s interests in the Idemitsu Officer Stockholders Committee.

8. The career summary of each Director is as of the preparation date (May 12, 2026) of these Reference Documents for the General Meeting of Shareholders.

9. JAPAN PULP AND PAPER COMPANY LIMITED, where Ms. Sumiko Takeuchi serves as an Outside Director, was found by the Japan Fair Trade Commission in March 2024 to have violated Article 3 of the Act on Prohibition of Private Monopolization and Maintenance of Fair Trade (prohibition of unreasonable restraint of trade) in connection with open tenders for recycled roll paper ordered by the National Printing Bureau, since at least June 2017. Said company has applied for leniency under the Commission’s penalty reduction and exemption program, and has received neither a cease-and-desist order nor a penalty payment order. As an Outside Director, Ms. Sumiko Takeuchi has actively made recommendations to the Board of Directors from an objective and impartial standpoint regarding the importance of compliance and risk management. Following the discovery of the aforementioned matters, she has continued to offer guidance on

preventing recurrence and has regularly monitored said company’s overall compliance efforts, thereby fulfilling her responsibilities.

Proposition No. 2: Election of two (2) Audit & Supervisory Board Members

The term of office of Audit & Supervisory Board Members Mr. Hidefumi Kodama and Ms. Yumiko Ichige will expire at the close of this Ordinary General Meeting of Shareholders. Hence, it is hereby proposed that two (2) Audit & Supervisory Board Members be elected.

The Audit & Supervisory Board has given their consent for this proposition. The candidates for Audit & Supervisory Board Members are as follows:

(Notes) 1. There is no special relationship between the candidates for Audit & Supervisory Board Member and the Company.

1. Ms. Yumiko Ichige is a candidate for Outside Audit & Supervisory Board Member.

2. Ms. Yumiko Ichige currently serves as an Outside Audit & Supervisory Board Member of the Company, and her term of office as an Audit & Supervisory Board Member will be four years at the conclusion of this Ordinary General Meeting of Shareholders.

3. Under Article 427, Paragraph 1 of the Companies Act of Japan, the Company has entered into an agreement with Ms. Yumiko Ichige to limit the liability for damages provided for in Article 423, Paragraph 1 of the Companies Act of Japan. Under the agreement, the liability is limited to the amount provided for under law. If the reelection of Ms. Yumiko Ichige is approved, the Company plans to continue the agreement.

4. The Company has entered into a liability insurance contract for Directors and Audit & Supervisory Board Members with an insurance company pursuant to Article 430-3, Paragraph 1 of the Companies Act of Japan. Under said insurance contract, the insurance company shall compensate for damages that may result from the insured (including the Audit & Supervisory Board Members of the Company) assuming responsibility in connection with the execution of their duties or receiving claims related to the pursuit of such responsibility. In the event that each candidate is elected and assumes office as an Audit & Supervisory Board Member, they will be insured under said insurance contract. Said insurance contract will be renewed on the same terms at the next renewal.

5. The number of shares of the Company held by Mr. Yoshitaka Onuma includes his interests in the Idemitsu Employee Stockholders Committee.

6. Ms. Yumiko Ichige satisfies the requirements for independent officers set by the Tokyo Stock Exchange, and the Company has registered her as an independent officer with the Tokyo Stock Exchange.

7. The career summaries of each candidate for Audit & Supervisory Board Member are as of the preparation date (May 12, 2026) of these Reference Documents for the General Meeting of Shareholders.

(Reference) Skills career matrix of Directors and Audit & Supervisory Board Members (assuming each candidate is elected at this General Meeting of Shareholders)

While fulfilling its social mission of providing a stable energy supply, the Company wishes to contribute to the realization of a carbon neutral society in 2050, and to utilize this as a business opportunity and improve to become a corporate entity that continues to grow sustainably. To this end, it is very important for Directors and Audit & Supervisory Board Members, who have various knowledge and experience, to actively discuss matters at the Board of Directors meetings, and enhance the quality of discussions regarding overall management strategies including human capital strategies.

Since preparing and disclosing the skills career matrix for Directors in 2020, we have periodically reviewed it in light of the management challenges we face and the areas of expertise expected of Directors and Audit & Supervisory Board Members, and have identified the areas set out in the table below. The Company elected Officers who have skills, such as knowledge and experience in those areas, while also paying attention to diversity. For the areas that the Board of Directors members do not have sufficient skills (issues concerning economic security or other areas for which high expertise is required), the Company supplements them by inviting outside experts to Advisory Board meetings and Officer training sessions.

Shunichi Kito

Director

Noriaki Sakai

Atsuhiko Hirano

Masahiko Sawa

Takashi Sakata

Kazuma Ikeda

Masakazu Idemitsu Kazunari Kubohara

Audit & Supervisory Board Members

Nami Kitamura

Yoshitaka Onuma

Outside

Yumiko Ichige

Independent

Outside

Masahiko

Tezuka

Independent

indicates areas to which the Company particularly expects the relevant Director or Audit & Supervisory Board Member to contribute. It does not represent the full scope of that person’s skills and experience.

(Reference)

Independence Requirements for Outside Officers

Independent Outside Officers must not fall under any of the following:

1. A person who has become an executive officer of the Company or its subsidiaries in the present or in the past.

2. A person who is a major shareholder or currently affiliated with an organization that is a major shareholder with a 10% or higher share ratio in the Company’s latest shareholder list.

3. A person who is currently affiliated with the Company’s business partners with a total annual transaction amount of 2% or more of consolidated net sales in the three most recent business years or their consolidated subsidiaries.

4. A person who is a consultant, accounting professional, legal expert, accounting auditor, or contractor (or, if such person belongs to the corporations, associations, or other organizations, an individual who actually belongs to those organizations whose average annual transaction amount with the Company is 2% or more of the organization’s total sales or gross in the three most recent business years) who receives money or other properties of ¥10 million or more per annum from the Company other than remuneration for a Director or for an Audit & Supervisory Board Member in the three most recent fiscal years.

5. A person who is currently affiliated with non-profit organizations that have received 2% or more of their gross or ordinary income from the Company in the three most recent fiscal years.

6. In the case where a person has belonged to any of the organizations or business partners described in “2.” to “5.” above, three years have not elapsed since (s)he left the organization or business partner.

7. A person who is the spouse or relative within the third degree of kinship of an officer (excluding those that are not important) of the Company or a specified associated company of the Company.

Proposition No. 3: Revision of the Terms of Performance-Linked Stock Compensation, etc. for Directors, etc.

1. Reasons for the proposal and reasons why we consider revision of said compensation, etc. is appropriate

   The Company introduced a performance-linked stock compensation plan (“the Plan”) under which Company shares are granted based on job title, achievement of performance targets, and other criteria for the Company’s Directors (excluding non-Executive Directors, Outside Directors, and non-residents of Japan; the same applies hereinafter in this proposition) and Executive Officers at Senior Executive Officer level or above (excluding non-residents of Japan; the same applies hereinafter in this proposition) (collectively, “Directors, etc.”) to strengthen their commitment to improving the Company’s medium-to long-term performance and enhancing corporate value, with the approval of shareholders at the 103rd Ordinary General Meeting of Shareholders held on June 28, 2018. Most recently, at the 108th Ordinary General Meeting of Shareholders held on June 22, 2023, we revised the performance indicators under the Plan to align with the key indicators in the Company’s Medium-term Management Plan, etc.

   In May 2026, we announced a new Medium-term Management Plan (FY2026-2030) (“the Medium-term Management Plan”). In order to realize the Medium-term Management Plan, we propose to continue to align the performance indicators under the Plan with the key indicators of the Medium-term Management Plan, as we have done in the past, while setting stock-based compensation for Directors, etc. at a market-competitive level, thereby strengthening their commitment to improving the Company’s medium- to long-term performance and enhancing corporate value as well as encouraging their holding of Company shares, further heightening the sense of shared interest with our shareholders. As we wish to continue the Plan after its revision (“Revision of the Plan”) as described in “2. Amount and content of compensation, etc. after the Revision of the Plan,” we ask for your approval of this proposition.

   Please note that compensation described in this proposition is separate from the compensation limit for Directors approved at the 91st Ordinary General Meeting of Shareholders held on June 27, 2006 (at ¥1.2 billion or less per year), and will be provided to Directors, etc. in the form of stock-based compensation.

   The Revision of the Plan aims to further strengthen the commitment of Directors, etc. to improving the Company’s medium- to long-term performance and enhancing corporate value by reinforcing the link between the Medium-term Management Plan and the compensation for Directors, etc., and we therefore consider the contents of this proposition to be appropriate. Furthermore, at the Board of Directors meeting held on May 12, 2026, we resolved to revise the policy for determining the individual compensation of Directors, etc. The outline of the revised policy is set out at the end of this proposition, which contains the necessary and reasonable terms for determining individual compensation for Directors, etc., in accordance with that policy. Furthermore, in order to ensure transparency and objectivity in the compensation determination process, we have established a Nomination and Compensation Advisory Committee, composed of independent Outside Directors, as a voluntary advisory body to the Board of Directors. The Revision of the Plan has been deliberated by the Nomination and Compensation Advisory Committee, with a recommendation submitted to the Board of Directors.

   If Proposition 1, “Election of 13 Directors,” is approved as originally proposed, the number of Directors eligible under this Plan will be six (6). Furthermore, as noted above, the Plan also includes compensation for Executive Officers at Senior Executive Officer level or above (currently, there are 11 Executive Officers at Senior Executive Officer level or above who do not concurrently serve as Directors, eligible under the Plan). We are proposing the overall amount and content of compensation under the Plan, taking into

   account the possibility that these Executive Officers at Senior Executive Officer level or above may be newly appointed as Directors after the Plan starts.

2. Amount and content of compensation, etc. after the Revision of the Plan

   In order to continue the Plan, we wish to revise some of the Plan’s contents as follows. Please note that, with the exception of the revisions described below, the contents of the Plan will essentially remain the same as those of the Plan revised in FY2023.

   (Underlined text indicates changes.)

   	Current	As Revised
   Maximum amount contributed	the amount calculated by multiplying JPY640 million per year by the number of years in the applicable period	the amount calculated by multiplying JPY920 million per year by the number of years in the applicable period
   Indicators used to calculate the Company’s shares, etc. granted to the Directors, etc.		non-financial indicators in accordance with the company’s materiality—such as indicators essential for CO2 reduction, and indicatorsfor employee engagement that assess efforts toward maximizing employee growth and fulfillment.

   • The indicators used to measure the degree of achievement of the performance targets are those highlighted in the Company’s medium- to longterm vision and the medium-term management plan.

   • The indicators for the initial applicable period after the Plan Revision include the financial indicators related to the transformation of the business portfolio (ROIC, ROE, and the ratio of fossil fuel business revenue), as well as non-financial indicators essential for achieving carbon neutrality (CO2 reduction and employee engagement indicators that assess initiatives aimed at maximizing employee growth and fulfillment).

   • The indicators used to measure the degree of achievement of the performance targets are those highlighted in the Company’s medium- to longterm vision and the medium-term management plan, as well as those that promote value sharing with shareholders shareholder value indicators, are selected.

   • The indicators for the initial applicable period after the Plan Revision, particular emphasis is placed on aligning with the medium-term management plan (FY2026–FY2030) from the perspective of value sharing with shareholders and sustainable enhancement of corporate value. Specifically, the evaluation consists of various financial indicators related to capital efficiency (ROIC, ROE), as well as

   (*) The maximum number of shares of the Company to be acquired for granting, etc., to Directors, etc., was approved at the 108th Ordinary General Meeting of Shareholders held on June 22, 2023, as “the number of shares equivalent to the number obtained by multiplying the maximum number of points per business year, 200,000 points (equivalent to 200,000 shares), by the number of years in the applicable period.” However, as a result of the stock split carried out by the Company with an effective date of January 1, 2024 (where one share was split into five shares), the limit has been adjusted to “the number of shares equivalent to the number obtained by multiplying the maximum number of points per business year, 1,000,000 points (equivalent to 1,000,000

   shares), by the number of years in the applicable period.”

   1. Overview of the Plan

      The Plan is a share-based compensation plan in which a trust (“the Trust”) acquires the Company’s shares using funds contributed by the Company as compensation for Directors, etc., and then grants and delivers (“Deliver/Delivery, etc.”) the Company’s shares and cash corresponding to the proceeds from the sale of those shares (“the Company’s Shares, etc.”) to Directors, etc. In principle, the time of Delivery, etc. of the Company’s shares to Directors, etc. will be after their retirement.

   2. Maximum amount the Company will contribute

      The applicable period of the Plan (“Applicable Period”) will be the fiscal years covered by the Company’s Medium-term Management Plan. The initial Applicable Period following the Revision of the Plan shall be the five (5) fiscal years from FY2026 (April 2026 to March 2027) to FY2030 (April 2030 to March 2031) covered by the Medium-term Management Plan (FY2026-2030). For each Applicable Period, the Company will contribute an amount up to ¥920 million multiplied by the number of years in that Applicable Period (¥4.6 billion for the initial Applicable Period of five (5) fiscal years following the Revision of the Plan) as compensation for Directors, etc., and will establish a trust for the period corresponding to the Applicable Period, with Directors, etc. who meet the beneficiary requirements as beneficiaries (including the continuation of the Trust described in the second paragraph of this section (2); the same applies hereinafter). The Trust will acquire the Company’s shares from the stock market or from the Company (through the disposal of treasury shares) using the entrusted funds as the source of capital, in accordance with the instructions of the trust administrator. Any additional shares of the Company acquired during the initial Applicable Period following the Revision of the Plan will be purchased from the stock market, so no share dilution will result. During each year of the Applicable Period, the Company will grant points (as defined in (3) below) to Directors, etc. Upon retirement of the Directors, etc., the Trust will Deliver, etc., the Company’s Shares, etc., corresponding to the value of the accumulated granted points (“Accumulated Points”) (however, in the event of the death of a Director, etc., this will occur at the time of death; the same applies hereinafter). Upon expiration of the trust period of the Trust, the Company may, instead of establishing a new trust, continue the existing Trust by amending the trust agreement and making additional contributions. In such case, the number of years corresponding to the Medium-term Management Plan then in effect will constitute the new Applicable Period, and the trust period of the Trust will be extended by the same period as that new Applicable Period. For each extended trust period, the Company will make additional contributions in an amount up to ¥920 million multiplied by the number of years in that new Applicable Period and will continue to grant points to Directors, etc., during the extended trust period; and the Trust will continue to Deliver, etc. the Company’s Shares, etc. However, when such additional contributions are made, if there are any remaining Company shares (excluding Company shares corresponding to points already granted to Directors, etc. but not yet Delivered, etc.) or cash (“Remaining Shares, etc.”) in the trust assets at the end of the trust period prior to the extension, the combined total of such Remaining Shares, etc. and the additionally contributed trust funds shall not exceed ¥920 million multiplied by the number of years in that new Applicable Period. If the trust agreement is not amended and no additional contributions are made at the end of the trust period (or the extended trust period, if the Trust is continued), no further points

      will be granted to Directors, etc. However, if there are any Directors, etc. in office at that time who may meet the beneficiary requirements, the trust period of the Trust will be extended for a certain period until such Directors, etc. retire and the Delivery, etc. of the Company’s shares is completed. However, even in such cases, no new points will be granted to such Directors, etc.

   3. Calculation method and upper limit of the number of the Company’s shares to be delivered to Directors, etc. (including the number of shares subject to liquidation) The number of the Company’s shares to be Delivered, etc. to Directors, etc. (including the number of shares subject to liquidation) shall be determined based on Accumulated Points. One (1) point shall correspond to one (1) share (fractions of less than 1 point shall be rounded down), and if the number of the Company’s shares held in the Trust increases or decreases due to a stock split, allotment of shares without contribution, a consolidation of shares, etc., the Company shall adjust the number of the Company’s shares Delivered, etc. per point (including the number of shares subject to liquidation) in proportion to such increase or decrease.

      During the trust period, Directors, etc. will be granted points at a fixed time each year, calculated by multiplying the predetermined base points for each position by a payment rate reflecting the degree of achievement of the performance targets for each fiscal year within the Applicable Period. The indicators used to measure the degree of achievement of performance targets are selected from those emphasized in the Company’s medium- to long-term vision and Medium-term Management Plan, as well as shareholder value indicators that promote value sharing with shareholders. For the initial period following the Revision of the Plan, particular emphasis is placed on alignment with the Medium-term Management Plan (FY2026-2030) from the perspective of value sharing with shareholders and sustainable corporate value enhancement. Specifically, it consists of various indicators related to capital efficiency (ROIC, ROE) as financial indicators, and various indicators aligned with the materiality set by the Company as non-financial indicators, including CO2 reduction and employee engagement indicators assessing efforts to maximize employee growth and engagement.

      Base points are calculated as follows: “Base amount determined for each position ÷ Average closing price of the Company’s shares on the Tokyo Stock Exchange in July 2026 (fractions of a decimal point are rounded down).” If the trust period is extended, the average closing price of the Company’s shares on the Tokyo Stock Exchange for the month preceding the first month of the fiscal year in which the extension begins shall apply. Also, the points granted are calculated as follows: “Base points × payment rate reflecting the degree of achievement of performance targets.” For Directors etc. who meet the beneficiary requirements, the Trust shall Deliver, etc. the Company’s Shares, etc. corresponding to their Accumulated Points after their retirement.

      The total number of points granted to Directors, etc., during the trust period of the Trust shall be capped at 1,000,000 points multiplied by the number of years in the Applicable Period. Furthermore, the number of the Company’s shares acquired by the Trust for Delivery, etc. to Directors, etc. during the trust period shall be limited to the number of shares corresponding to said maximum number of points. Accordingly, for the initial trust period following the Revision of the Plan, the number of shares will be capped at 5,000,000 (calculated by multiplying the number of years (5) in the trust period). This cap on the number of shares is determined based on recent stock prices, etc., and taking into account the limit on trust fund assets described in (2) above. If the Trust described in the second paragraph of (2) above is continued, the maximum number of points that may be granted to Directors, etc.

      during the extended trust period shall be 1,000,000 points multiplied by the number of years in the new Applicable Period, and the number of the Company’s shares acquired by the Trust for Delivery, etc. to Directors, etc. during the trust period shall correspond to said maximum number of points. Furthermore, if any point adjustments described in the first paragraph of this section (3) are carried out, the maximum number of the Company’s shares that the Trust may acquire for Delivery, etc. to Directors, etc. will also be adjusted accordingly.

   4. Method and timing of Delivery, etc. of the Company’s Shares, etc. to Directors, etc. Directors etc. who meet the beneficiary requirements shall, after their retirement, receive Delivery, etc. of the Company’s Shares, etc. from the Trust corresponding to their Accumulated Points. At that time, the Directors, etc. will receive delivery of the Company’s shares corresponding to 70% of their Accumulated Points (with shares less than one share unit rounded down), and the remaining portion will be liquidated within the Trust, with the cash corresponding to the proceeds from such liquidation delivered to the Directors, etc. Furthermore, if a Director, etc. who meets the beneficiary requirements dies during the trust period, the number of the Company’s shares corresponding to the Accumulated Points at that time will be liquidated within the Trust, with the cash corresponding to the proceeds from such liquidation delivered to the heirs of that Director, etc. Furthermore, if a Director, etc. who meets the beneficiary requirements is assigned to an overseas post during the trust period, the number of the Company’s shares corresponding to the Accumulated Points at that time will be liquidated within the Trust, with the cash corresponding to the proceeds from such liquidation delivered to that Director, etc.

   5. Voting rights relating to the Company’s shares within the Trust

      With respect to the Company’s shares held in the Trust (i.e., the Company’s shares prior to their Delivery, etc. to Directors, etc. in accordance with (4) above), voting rights shall not be exercised during the trust period in order to ensure management neutrality.

   6. Clawback scheme, etc.

      If any Director, etc. commits serious misconduct or a violation, the Company may forfeit the beneficiary rights to shares to be delivered under this Plan (malus) and require the Director, etc. to return money equivalent to the Company’s shares, etc. already delivered (clawback).

   7. Other details regarding the Plan

Other details regarding the Plan shall be determined by the Board of Directors at the time the Trust is established, upon any amendment of the trust agreement, or each time additional contributions are made to the Trust.

For further details regarding the Plan, please refer to the following disclosures: “Notice Regarding the Continuation and Revision of the Performance-Linked Stock Compensation Plan” dated May 12, 2026; “Notice Regarding the Continuation and Revision of the Performance-Linked Stock Compensation Plan” dated May 9, 2023; “Notice Regarding the Continuation and Partial Revision of the Performance-Linked Stock Compensation Plan” dated May 10, 2022; “Notice Regarding Partial Revision of the Performance-Linked Stock Compensation Plan and Contribution of Additional Trust Funds” dated May 15, 2019; and “Notice Regarding the Introduction of a Performance-Linked Stock Compensation Plan” dated May 15, 2018.

(Reference)

“Policy for Determining Details of Compensation, etc. for Individual Directors, etc.”

(Basic Policy on Executive Compensation)

The Company’s basic policy on compensation for its Directors and Executive Officers (at Senior Executive Officer level or above) (“Directors, etc.”) is to: a) enhance corporate performance and value over the medium to long term in order to realize the Group’s management vision; and b) establish a compensation system and decision-making process that are transparent, rational and fair, enabling the Company to fulfill its accountability to customers, society, the environment, shareholders, business partners, employees, and other stakeholders. Based on this basic policy, the Company resolved at a meeting of the Board of Directors held on May 12, 2026 to revise the policy for determining the details of compensation, etc. for individual Directors, etc., as described below. With respect to the determination of compensation, etc. for individual Directors, etc., the Company has established a Nomination and Compensation Advisory Committee, composed of independent Outside Directors, as a voluntary advisory body to the Board of Directors. The Nomination and Compensation Advisory Committee has conducted a multi-faceted review of the original draft concerning the matter, including whether the contents are aligned with said policy for determining compensation. The Board of Directors respects the recommendations of the Nomination and Compensation Advisory Committee, and believes the contents to be aligned with said policy for determining compensation.

(Compensation Standard)

Compensation levels for Directors, etc. shall be reviewed as appropriate in light of changes in the business environment and external survey data, with a view to attracting, retaining, and appropriately incentivizing talent capable of contributing to the achievement of the Company’s medium- to long-term management vision.

(Compensation Structure)

The compensation system for the Company’s Directors (excluding non-Executive Directors and Outside Directors) and Executive Officers at Senior Executive Officer level or above is designed to promote business portfolio transformation, enhance capital efficiency, and advance environmental, social, and governance initiatives, thereby leading to the further enhancement of corporate value and the achievement of the medium- to long-term management vision. Specifically, to appropriately evaluate management efforts to enhance corporate value over the medium to long term with due emphasis on both short-term and medium- to long-term performance, the compensation system comprises (1) fixed compensation, (2) performance-linked bonuses, and (3) performance-linked stock compensation. The ratios of the respective compensation at the time of standard payment are set at approximately (i) 50%, (ii) 25%, and (iii) 25%. Compensation for non-Executive Directors and Outside Directors consists solely of fixed compensation from the perspective of ensuring appropriate supervisory functions for assessing the appropriateness of business execution from an objective standpoint.

Fixed compensation shall be paid on a monthly basis in an amount determined according to the role and responsibilities.

Performance-linked bonuses are designed to fluctuate within a range of 0 - 200% according to the degree of achievement of the Company’s major financial indicators (Profit before tax excluding financial expenses (“Profit before tax”)) and non-financial indicators (human capital-related indicators proposed in the Medium-term Management Plan, etc.), and the degree of achievement of Directors’ “activity goals” set by respective management members taking into account their roles and duties (important strategic tasks toward structural reforms) and the “goals for the responsible area” of Executive Officers (at Senior Executive Officer level or above). Performance-linked bonuses will be granted in June every year.

From the perspective of sharing value with shareholders and continued improvement of corporate value, performance-linked stock compensation places a particular emphasis on the link with the Vision for 2030 and the Medium-term Management Plan (FY2026-2030) as well as with shareholder value. Specifically, performance-linked stock compensation is designed to fluctuate within the range of 0 -200% in accordance with the degree of achievement concerning such financial indicators related to business portfolio rearrangement as ROIC and ROE, and such non-financial indicators determined in accordance with materiality to the Company as indicators for measuring CO2 reduction essential for the realization of carbon neutrality and a circular society, and those for measuring engagement of employees to evaluate efforts toward maximization of employees’ growth and engagement.

Furthermore, to ensure that this serves as an incentive for Directors, etc. to enhance corporate value from a medium- to long-term perspective, the shares will be delivered to Directors, etc. after their retirement.

The policy provides that, in the event a Director, etc. engages in serious misconduct or a violation, the Company may forfeit the beneficiary rights of the Director, etc. to shares to be delivered as performance-linked stock compensation (malus) and may require the Director, etc. to return money equivalent to the Company’s shares, etc. already delivered (clawback).

The indicators and their respective assessment weightings for performance-linked bonuses and performance-linked stock compensation are set forth in the table below; we consider this configuration of indicators appropriate for achieving sustainable enhancement of the Company’s corporate value.

*The figures in parentheses for performance-linked bonuses represent the weighting for Senior Executive Officers

BUSINESS REPORT

(April 1, 2025 to March 31, 2026)

1. Current status of Idemitsu Group (the “Group”)

1. Business overview:

   Consolidated Financial Results for FY2025 (From April 2025 to March 2026)

   FY2025

   [111th year]

   Net sales

   Operating Income + Equity

   Income

   ¥8,105.9 billion

   ¥214.7 billion

   (¥244.1 billion)

   ¥171.9 billion

   (¥192.3 billion)

   (In brackets: Excludes inventory impact)

   Net Income Attributable to Owners of the Parent

   (In brackets: Excludes inventory impact)

   FY2024

   [110th year]

   ¥9,190.2 billion ¥184.8 billion

   (¥214.7 billion)

   ¥104.1 billion

   (¥124.8 billion)

   During the current fiscal year, the Japanese economy was on a moderate recovery trend, supported by improvements in employment and income conditions. Meanwhile, close attention must continue to be paid to developments in U.S. trade policy and foreign exchange rates, and the worsening situation in Iran and the blockade of the Strait of Hormuz in the Middle East have led to instability in crude oil prices and energy demand. As a result, the business environment surrounding corporate activities remains uncertain.

   Crude oil prices fell due to concerns about economic deterioration, mainly following the announcement of tariffs by the United States in early April 2025, as well as the perception of oversupply after OPEC Plus announced production increases.

   However, prices began to rise in June due to geopolitical risks stemming from the situation in Iran and Israel, and the tightening of U.S. sanctions against Russia. From the end of February 2026, they rose sharply over a short period due to the worsening situation in Iran and the blockade of the Strait of Hormuz. As a result, the average Dubai crude oil price fell by $6.7/bbl to $71.8/bbl.

   The yen initially appreciated against the U.S. dollar, the yen had strengthened due to economic deterioration following the announcement of tariffs by the United States, as well as speculation that the U.S. government may let the dollar fall. Since then, however, the yen has repeatedly risen and fallen, affected by the U.S. government’s tariff negotiations and geopolitical risks stemming from the situation in Iran and Israel. Since the inauguration of the Takaichi administration, the yen has depreciated due to proactive fiscal policy and monetary easing, and the worsening situation in Iran has further weakened the yen. Consequently, the average exchange rate against the dollar decreased by ¥1.9/$ from the previous fiscal year to ¥150.7/$.

   Australian thermal coal spot prices remained below the previous year’s levels throughout the year. As a result, the average price fell by $29.4/ton from the previous fiscal year to $105.4/ton.

   In this environment, consolidated net sales for FY2025 amounted to ¥8,105.9 billion, a decline of ¥1,084.3 billion from the previous fiscal year, mainly due to falling crude oil prices in the petroleum segment.

   Operating income + equity income (excluding inventory impact) increased by

   ¥29.4 billion from the previous fiscal year to ¥244.1 billion, mainly because the positive time lag effects from the sharp rise in crude oil prices in the petroleum segment

   outweighed the impact of the decline in coal market conditions in the resources segment.

   Net income (excluding inventory impact) was ¥192.3 billion, up by ¥67.5 billion from the previous fiscal year.

   Net income including inventory impact amounted to ¥171.9 billion, up by ¥67.8 billion from the previous fiscal year.

   (billion yen)

   	Petroleum	Basic chemicals	Functional materials	Power and renewable energy	Resources	Other	Total
   FY2025	207.1	(6.8)	33.4	(1.8)	33.1	(20.9)	244.1
   FY2024	152.0	(8.0)	28.2	(12.3)	77.4	(22.7)	214.7

   • Petroleum segment

     In the petroleum segment, despite increased expenses from large-scale periodic repairs, positive time lag effects from the rise in crude oil prices due to the situation in the Middle East resulted in income of ¥207.1 billion (up ¥55.1 billion from the previous fiscal year).

   • Basic chemicals segment

     The basic chemicals segment posted loss of ¥6.8 billion (up ¥1.1 billion from the previous fiscal year), as product margins remained at low levels, despite positive time lag effects caused by the sharp rise in naphtha prices in March.

   • Functional materials segment

     The functional materials segment posted income of ¥33.4 billion (up ¥5.2 billion from the previous fiscal year), mainly due to strong overseas sales of lubricants business and the contributions from acquisition of AGRO-KANESHO CO., LTD. as a wholly owned subsidiary in the agri life business.

   • Power and renewable energy segment

     The power and renewable energy segment posted loss of ¥1.8 billion (up ¥10.5 billion from the previous fiscal year), mainly due to improved earnings following the resolution of power plant issues in the previous year and a reduction in depreciation expenses resulting from impairment losses on biomass power generation facilities.

   • Resources segment

   The oil/natural gas exploration and production business posted income of ¥14.0 billion (down ¥4.6 billion from the previous fiscal year) mainly due to a decline in crude oil prices. The coal business posted income of ¥19.1 billion (down ¥39.6 billion from the previous fiscal year), mainly due to price factors associated with a decline in the coal market. As a result, segment income was ¥33.1 billion (down ¥44.2 billion from the previous fiscal year).

Consolidated Balance Sheet (billion yen)

Points

• Total assets as of March 31, 2026 increased by ¥553.2 billion from the end of the previous fiscal year, mainly due to the acquisition of Fuji Oil Company, Ltd. as a subsidiary.

• Although interest-bearing debt increased due to investments and an increase in working capital associated with the acquisition of Fuji Oil Company, Ltd. as a subsidiary, net assets also increased mainly due to net income, and the Net D/E ratio remained at 0.62, the same level as the previous year.

  Cash Flows (CFs) (billion yen)

  Points

• CF from operating activities was positive, at

  +¥392.4 billion, due to the recording of net income. CF from investing activities was negative, at -¥291.6 billion, due to the acquisition of fixed assets, etc., resulting in a free CF of ¥100.8 billion.

• CF from financing activities was negative, at

  -¥104.9 billion, due to the repayment of interest-bearing debts, shareholder returns such as dividends and share repurchases, etc.

• As a result, the ending balance of cash and cash equivalents decreased by ¥7.2 billion from the beginning of the period.