OpenAI has provided Japanese banks with access to its latest GPT 5.5 model to strengthen defenses against escalating cyberattacks. The decision was confirmed on May 29, 2026, by Japanese Finance Minister Satsuki Katayama, following a meeting in Tokyo with Jason Kwon, OpenAI's Chief Strategy Officer. This partnership stems from negotiations between the Japanese and United States governments, mirroring previous access granted to European firms.

While specific institutions were not named by the Minister, reports indicate that Japan’s three largest financial entities—Sumitomo Mitsui Banking Corp, Mizuho Bank, and MUFG Bank—are expected to utilize the technology. The deployment serves as a strategic defensive measure, as modern AI models capable of advanced coding present significant risks by enabling hackers to identify and exploit software vulnerabilities with high efficiency. Authorities view early access to these models as a crucial step for protecting financial infrastructure.

The Japanese government has established a public-private working group to monitor cybersecurity risks, and Minister Katayama suggested that the state may also gain access to advanced models to enhance national defense. Although MUFG and Mizuho declined to comment, the initiative aligns with broader efforts to bolster cybersecurity capabilities across the sector. Future plans may involve commissioning advanced AI systems to additional companies to further secure the financial ecosystem against evolving digital threats.

OpenAI has provided Japanese banks with access to its latest GPT 5.5 model to strengthen defenses against escalating cyberattacks. The decision was confirmed on May 29, 2026, by Japanese Finance Minister Satsuki Katayama, following a meeting in Tokyo with Jason Kwon, OpenAI's Chief Strategy Officer. This partnership stems from negotiations between the Japanese and United States governments, mirroring previous access granted to European firms.

While specific institutions were not named by the Minister, reports indicate that Japan’s three largest financial entities—Sumitomo Mitsui Banking Corp, Mizuho Bank, and MUFG Bank—are expected to utilize the technology. The deployment serves as a strategic defensive measure, as modern AI models capable of advanced coding present significant risks by enabling hackers to identify and exploit software vulnerabilities with high efficiency. Authorities view early access to these models as a crucial step for protecting financial infrastructure.

The Japanese government has established a public-private working group to monitor cybersecurity risks, and Minister Katayama suggested that the state may also gain access to advanced models to enhance national defense. Although MUFG and Mizuho declined to comment, the initiative aligns with broader efforts to bolster cybersecurity capabilities across the sector. Future plans may involve commissioning advanced AI systems to additional companies to further secure the financial ecosystem against evolving digital threats.