Ookuma Diamond Device

Ookuma Diamond Device is a deep-tech semiconductor startup founded in 2022 and headquartered in Sapporo, Hokkaido, Japan. The company is pioneering the commercialization of diamond semiconductor devices — a material often called the 'ultimate semiconductor' for its ability to operate in extreme environments including high temperatures, high radiation, and high power densities where conventional silicon and GaN technologies face fundamental limits. Founded by researchers from Hokkaido University and AIST, Ookuma Diamond Device's technology originated from Japan's national challenge of decommissioning the Fukushima Daiichi Nuclear Power Plant, where electronics must withstand extreme heat and radiation. The company completed the world's first diamond semiconductor manufacturing facility in Okuma, Fukushima in May 2026. Its primary product targets include defense radar systems (5x output vs GaN, 1.5x radar detection range), space applications (small SAR satellites — selected for JAXA's Space Strategy Fund), and next-generation communications infrastructure. The company has been selected for the Japan–U.S. Innovation Awards and the Arlington Tech Launchpad 2026 Cohort, reflecting its international defense and aerospace ambitions. Investor: Coral Capital.