Idemitsu Kosan : Notice Concerning the Postponement of the Announcement Schedule for the Next Medium-term Management Plan

Press Release

March 13, 2026

Company Name: Idemitsu Kosan Co.,Ltd.

Representative Director and President: Noriaki Sakai (Company Code: 5019, TSE Prime Market)

Contact person: Shinko Sasaki, General Manager, Investor Relations Office, Finance Department Telephone: +81-3-3213-9307

Idemitsu Kosan Co.,Ltd (the "Company") hereby announces that the company decided to postpone the announcement schedule for the next medium-term management plan from March 17, in light of the current situation.

The company originally planned to announce the next medium-term management plan covering fiscal years 2026 and beyond on March 17, 2026, as the current plan covers the three-year period from fiscal 2023 to fiscal 2025.

However, the current environment surrounding crude oil price trends and petroleum product supply has become increasingly severe against the backdrop of the recent escalation in the Middle East situation. Under these circumstances, the Company decided to postpone the announcement of the medium-term management plan in order to focus on fulfilling our social responsibility of ensuring stable supplies of energy and materials.

The announcement date for the medium-term management plan is now scheduled for May 12, 2026, coinciding with the announcement of our full-year results for fiscal 2025.

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