PRESS RELEASE
Sony Bank and Fujitsu apply Generative AI to Core Banking System Development
Achieving 30% reduction in development period from basic design to integration testing
Sony Bank, Inc.
Fujitsu Limited
Tokyo and Kawasaki, Japan, September 14, 2026
Sony Bank, Inc. (Sony Bank) and Fujitsu Limited (Fujitsu) today announced the full-scale application of generative AI in the development of Sony Bank's core banking system, starting in September 2025. By establishing a mechanism for AI to utilize development assets such as design documents, source code, and test assets, and gradually expanding its application to key processes from design to manufacturing and testing through actual development, the companies have confirmed a 30% reduction in the development period from basic design to integration testing as of July 2026, compared to conventional methods.
The system adopts Fujitsu's core banking solution, "Fujitsu Core Banking xBank"[1] ("Core Banking xBank"). "Core Banking xBank" features a cloud-native architecture operating on Amazon Web Services (AWS), providing an environment that enables rapid integration and trials with generative AI services. This environment allowed for the phased application of generative AI to each process.
In this initiative, an AI agent centered on Anthropic PBC's "Claude"[2] on “Amazon Bedrock”[3] is utilized across processes, with human oversight for final judgment and quality assurance. The use of generative AI is not limited to proof-of-concept (PoC) but has been established as a development process for a core banking system in live operation.
Sony Bank and Fujitsu will leverage the knowledge and development assets gained from this initiative to other processes and systems, further deepening and expanding the use of generative AI at Sony Bank. Fujitsu will also apply the knowledge gained from this initiative to future "Core Banking xBank" development and development for other financial institutions, contributing to the advancement of financial system development.
Background
It can take Japanese financial institutions several months to years to move from planning to launching new services, and high development costs and complex development processes have made it difficult to respond quickly to rapidly changing market environments. As generative AI matures, the ability to embed it into live development processes is becoming a competitive differentiator.
Amidst this, both companies, together with Amazon Web Services Japan (AWS Japan), have been promoting the transformation of the development process for core banking systems, which are the foundation of banking operations.
Overview of the Initiative
Starting in September 2025, Sony Bank and Fujitsu are utilizing Anthropic’s "Claude" model and other models provided on Amazon Bedrock. In this initiative, generative AI transforms the entire development process by leveraging design documents, source code, and test assets across all stages.
This initiative has resulted in a 40% reduction in man-hours and a 30% reduction in development period for processes from basic design to integration testing. Specifically, the companies confirmed up to a 90% reduction in impact assessment man-hours in the basic design phase, up to a 40% reduction in design document creation man-hours in the detailed design phase, a 99% source code generation rate in the implementation phase, and up to a 90% reduction in test execution man-hours in the integration testing phase.
- Transformation to an AI-centric development process
Generative AI is applied not only to specific processes such as coding but across major development processes including basic design, manufacturing/unit testing, and integration testing. Furthermore, an AI agent centered on "Claude" and "Claude Code"[4] on Amazon Bedrock utilizes development assets such as design documents, source code, and test assets of Sony Bank's core banking system across processes. By generating source code and test cases from design documents and reusing deliverables from upstream processes in subsequent processes, inter-process collaboration is strengthened, leading to improved development efficiency. In addition, each AI agent supports development by linking with necessary development assets and various tools[5], under human judgment, approval, and quality assurance, thereby achieving both quality and productivity.
- Application to to actual development, not just PoC
This initiative applies generative AI to the actual development of a live core banking system, not just to conceptual PoCs or limited trials. It is also utilized in the development of various applications that support banking operations, including online transaction processing and batch processing, demonstrating practical application regardless of processing type. Furthermore, by incorporating generative AI into the standard development process and having Fujitsu personnel with expertise in financial operations and system development evaluate and improve it at appropriate times, the scope of application is expanded while ensuring safety and quality.
- High compatibility with "Core Banking xBank"
The cloud-native and microservices-based architecture adopted by "Core Banking xBank" serves as a crucial foundation for leveraging generative AI. The environment operating on AWS enables rapid integration and verification with generative AI services, and the microservices structure allows for phased application and evaluation on a function-by-function basis. As a result, generative AI was continuously applied to each of the design, implementation, and testing processes, and its effectiveness was verified, leading to an expansion of its application scope.
Loading component...
Future Plans
Loading component...
Loading component...
Tatsuya Fukushima, Executive Officer, Sony Bank Incorporated comments:
Loading component...
Masaru Yagi, Corporate Executive Officer, EVP, Fujitsu Limited comments:
Loading component...
Yasuhiro Kose, Executive Officer, Amazon Web Services Japan comments:
Loading component...
Hidetoshi Tojo, Executive Officer, Head of Japan, Anthropic Japan G.K. comments:
Loading component...
Note
Loading component...
Related Links
Loading component...
Loading component...
Press Contacts
Fujitsu Limited
Public, Investor and Analyst Relations Division
Loading component...
All company or product names mentioned herein are trademarks or registered trademarks of their respective owners. Information provided in this press release is accurate at time of publication and is subject to change without advance notice.
Date: 14 September 2026
City: Tokyo and Kawasaki, Japan
Company: Sony Bank, Inc. and Fujitsu Limited
