[Okuma Diamond Device] The world's first diamond semiconductor factory is completed

Okuma Diamond Device Co., Ltd. (Headquarters: Sapporo, Hokkaido; Representative Director: Hisahisa Hoshikawa, hereinafter "the Company") has completed the "Okuma Diamond Device Fukushima Plant," which had been under construction in Okuma, Futaba-gun, Fukushima Prefecture, with a completion ceremony held on May 29, 2026.

This plant serves as a manufacturing base for the mass production of diamond semiconductors, the first of its kind in the world. As a key facility, it will enable the social implementation of the Company's diamond semiconductor technology, which has been researched and developed starting from the national challenge of decommissioning the Fukushima Daiichi Nuclear Power Station, not only into decommissioning but also into the fields of space, security, next-generation communications, and energy infrastructure.

Approximately 200 people, including representatives from relevant government ministries, local governments, research institutions, corporate partners, financial institutions, construction-related parties, and local community members, attended the completion ceremony to celebrate the facility's opening.

■ About Okuma Diamond Device Fukushima Plant

Diamond semiconductors are expected to be applied in fields where conventional semiconductors struggle, specifically in extreme environments requiring resistance to high radiation, high/low temperatures, and high output/thermal loads.

At this plant, the company will engage in the development and manufacture of diamond semiconductor elements and amplifiers for space, security, and next-generation communications, as well as diamond detectors aimed at ensuring safety management for decommissioning workers and obtaining information on fuel debris within reactors.

Furthermore, in Okuma Town and other areas affected by the nuclear accident where this plant is located, the company will contribute to job creation and regional revitalization, advancing the formation of new industries rooted in the Fukushima/Hamadori region.

[Facility Overview]
Name: Okuma Diamond Device Fukushima Plant
Location: 94-8 Harano, Shimono-gami, Okuma-machi, Futaba-gun, Fukushima Prefecture (within Okuma Central Industrial Base)
Structure: Two-story steel structure
Site Area: Approx. 5,800㎡
Building Area: Approx. 1,100㎡
Completion Date: May 29, 2026

■ About the Completion Ceremony

At the ceremony, after an opening address by our Representative Director Hisahisa Hoshikawa, we received congratulatory remarks from guests. The ceremony also featured a ribbon-cutting by guests and stakeholders to celebrate the completion of the Fukushima Plant.

Attendees included representatives from the Ministry of Economy, Trade and Industry, the Reconstruction Agency, the Acquisition, Technology and Logistics Agency, Fukushima Prefecture, Okuma Town, the Fukushima Institute for Research, Education and Innovation (F-REI), the Fukushima Innovation Coast Framework Promotion Organization, research institutions, universities, financial institutions, diamond semiconductor-related companies, and construction and local community members.

■ Summary of Congratulatory Remarks and Greetings (Excerpts)

State Minister of Economy, Trade and Industry, Toshiro Ino: "The completion of the world's first diamond semiconductor factory in Okuma, Fukushima, is a major milestone in connecting R&D achievements to manufacturing, mass production, and social implementation. Diamond semiconductors are a key next-generation semiconductor technology supporting Japan's industrial competitiveness and economic security, with expected deployment in broad fields such as decommissioning, space, security, and next-generation communications."

State Minister for Reconstruction, Ryuichi Seto: "I feel the great significance of establishing a world-class R&D and manufacturing base in Okuma Town, starting from decommissioning, which is one of the most important challenges of reconstruction. I have high expectations that new jobs will be created, people will gather, and industries leading to the future will grow."

Member of the House of Representatives, Ryutaro Sakamoto: "Hamadori once supported Japan's development through coal, thermal power, and nuclear power. Overcoming the earthquake and nuclear disaster, I am very proud that a new challenge is beginning, contributing to the world from Okuma Town through this world's first diamond semiconductor factory."

Deputy Mayor of Okuma, Yoshiyuki Takeda: "We believe that diamond semiconductors contributing to the safe and steady progress of decommissioning the Fukushima Daiichi Nuclear Power Station will significantly contribute to the reconstruction of Okuma Town and Fukushima Prefecture. We will deepen our cooperation with your company and build the future of the town together."

Chairman of the Liberal Democratic Party Semiconductor Caucus, Member of the House of Representatives, Daishiro Yamagiwa: "The realization of a production base for diamond semiconductors, which has been researched for many years, is a historic step for Japan's semiconductor industry. We hope this plant becomes the cornerstone that opens Japan's future."

Member of the House of Councillors, Masako Mori: "I sincerely congratulate you on the completion of the world's first diamond semiconductor factory in Okuma. I have deep respect for your company's efforts, which will create local jobs and serve as a powerful driving force for reconstruction."

Representative Director Hoshikawa: "I believe that creating new technology, jobs, and industries from the major challenge of decommissioning Fukushima Daiichi is the meaning of our challenge in Okuma. I believe it is our role to take root in this place, which could be said to be a departure from minus rather than from zero, and to take responsibility for true reconstruction."