News

Equity Participation in Mainmark Co., Ltd.

Mar. 24, 2026

We are pleased to announce that Mitsui & Co., Principal Investments Ltd. ("MCPI", Head Office: Chiyoda-ku, Tokyo, President and CEO: Nobuyuki Goto) has invested in Mainmark Co., Ltd. (“Mainmark”, Head Office: Edogawa-ku, Tokyo, Representative Director and President: Futoshi Kawaguchi) through an investment

Centered on the Teretek^® method*, which restores tilted concrete slab floors to a level condition without interrupting operations, Mainmark provides integrated, one-stop services ranging from proposal to construction.
Our solutions address a wide range of challenges for both private facilities—such as factories, warehouses, and retail stores—and public infrastructure including roads, airports, ports, schools, and defense facilities. Mainmark’s services include ground improvement and reinforcement beneath existing buildings, correction of building inclination, structural vibration analysis, and liquefaction countermeasure work.
Including its Head Office, Mainmark operates eight offices nationwide—in Osaka, Sapporo, Sendai, Niigata, Kanazawa, Nagoya, and Fukuoka—offering various construction solutions tailored to each customer’s needs.

With the aim of contributing to regional revitalization across Japan, MCPI has long focused on supporting the growth of companies with unique technologies. MCPI seeks to strengthen the management foundations and enhance the service quality of locally rooted companies that may face medium‑ to long‑term challenges such as labor shortages, digital transformation (DX), and business succession.
By leveraging the Mitsui & Co. Group’s extensive networks and knowledge, management resources, and M&A expertise, MCPI aims to provide solutions that enable the sustainable growth of regional companies.
Through this investment, MCPI will welcome Mainmark as a business partner and will further accelerate these initiatives.

Following the investment, MCPI plans to dispatch its staff as Board members and provide hands‑on, on‑site support to promote the wider adoption of Mainmark’s technologies and to further develop its business.
Mr. Futoshi Kawaguchi will continue to serve as Representative Director and President, working closely with the company’s officers and employees, as well as with MCPI, to pursue the company’s continued growth.

*A patented construction method in which rigid polyurethane resin is injected beneath concrete slab floors, using the resin’s expansive force to fill voids beneath the slab and restore sunken slabs to a level condition.