Mitsui Chemicals : 【Timely Disclosure】Notice Regarding Introduction of Corporate Fellow System

Company name: Mitsui Chemicals, Inc.

HASHIMOTO Osamu,

February 5, 2026

Name of representative:

Inquiries:

Representative Director and President (Securities code: 4183 :Prime Market)

TAKATAMA Yoshinori,

General Manager of Corporate Communications Division(Telephone: ＋81-3-6880-7500)

Mitsui Chemicals, Inc. (Tokyo: 4183; President & CEO: HASHIMOTO Osamu; "the Company") hereby announces that, at the Board of Directors meeting held today, the Company resolved to introduce Corporate Fellow System.

1. Introduction of Corporate Fellow system

   The Company abolished its Senior Advisor, Advisor system effective March 31, 2025, in order to further improvement of the transparency and effectiveness of management. At the same time, we believe that external activities undertaken by former directors and other executives ―such as serving in key positions at economic and industry organizations with which the Company maintains close relationships (hereinafter "External Activities")― will continue to contribute to the enhancement of the corporate value of the Company and its Group. Accordingly, the Company has decided to introduce Corporate Fellow system.

   The title "Corporate Fellow" refers to individuals to whom the Company delegates External Activities after their retirement from executive positions. Corporate Fellows serve without remuneration, on a part-time basis, and under fixed-term contracts. Their appointment and dismissal are resolved by the Board of Directors based on proposals determined by the Nomination Committee, which is chaired by and composed of a majority of independent outside Members of the Board.

   Corporate Fellow does not participate in the management of the Company or its Group from a corporate governance perspective.

2. Date of introduction

As of April 1, 2026