Sun Asterisk Inc. (Headquarters: Chiyoda-ku, Tokyo; Representative Director: Taihei Kobayashi; hereinafter "Sun*") has launched "Regen*" (pronounced "Regen"), a modernization solution that supports the safe and reliable renewal of legacy systems by leveraging its proprietary AI agent framework, "Sun* Takumi." This solution is an AI-driven renewal process that accurately executes "specification restoration," "code translation," and "parity testing to compare the equivalence of new and old systems," which have traditionally been difficult to automate. By implementing the strict engineering discipline that Sun* excels at, it strongly supports companies' digital transformation and sustainable business growth without losing any of the unique specifications or rules of currently operating systems. Through "Regen*," Sun* aims to contribute to companies' sustainable growth and business updates by supporting the visualization of black-boxed system assets and phased modernization, thereby inheriting them to the next generation while maintaining business value. ■ Background of Development Legacy systems, which many companies currently face, generate enormous costs simply for maintenance due to increasing security risks, difficulty in securing rare talent familiar with old technologies, and declining development speed. However, "big bang" type renewals that attempt to overhaul systems all at once carry a high risk of failure, and many projects have stalled in reality. The biggest cause of system renewal failures is the oversight of complex business rules and unique specifications that have become black boxes through years of operation, leading to an inability to correctly migrate the meaning and value of existing systems. Furthermore, code conversion using a single generative AI tool, which has been a recent trend, has been insufficient to maintain the context of the entire system and has made it difficult to uphold the strict discipline required for enterprise quality. To solv