Sony Bank and Fujitsu have transitioned generative AI from pilot to live deployment in their core banking system, reducing development time and man-hours significantly while maintaining human oversight, signalling a major shift in Japanese banking technology.
Sony Bank and Fujitsu have moved generative AI from pilot stage into live banking system development, saying the technology is now being used across the build of Sony Bank’s core platform. The companies said the work began in September 2025 and, by July 2026, had cut the time needed from basic design through integration testing by 30% compared with conventional methods. Fujitsu said the effort is built around its Core Banking xBank system, which runs on Amazon Web Services and is designed to make it easier to trial AI tools in a cloud-native environment.
According to Fujitsu’s earlier announcement in October 2025, the partners had already planned to spread generative AI across core banking development by April 2026, with an initial goal of trimming development times by 20%. A separate report from ACN Newswire said Sony Bank had completed its full cloud migration in May 2025, giving the project the technical base needed for broader AI use. The latest update suggests the deployment has advanced beyond those early targets, with the companies now describing the work as a standard part of production development rather than an experiment.
The companies said the system uses AI agents centred on Anthropic’s Claude model through Amazon Bedrock, while human staff retain responsibility for final checks and quality control. They said the approach has reduced man-hours by 40% overall, with up to a 90% drop in impact-assessment effort in basic design, up to a 40% cut in detailed design documentation, a 99% source-code generation rate in implementation, and up to a 90% reduction in test-execution work during integration testing.
Sony Bank said it intends to extend the approach to requirements definition, security, operations and maintenance, while also applying the lessons to peripheral systems. Fujitsu said it plans to reuse the method for other financial institutions adopting Core Banking xBank and to feed the experience into its wider AI platform for finance. The companies and their partners, including AWS Japan and Anthropic, are casting the project as a model for how Japanese banks can modernise while keeping the human oversight that regulators and customers expect.
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