We have developed a Scalable CI/CD Pipeline to address internal challenges related to Japan 2025 cliff problem, a critical issue where the mass end of service life of legacy core IT systems threatens to significantly increase the maintenance cost and black box nature of these system also leads to difficult update moreover replace, which leads to lack of progress in Digital Transformation (DX). If not addressed, Japan could potentially lose up to 12 trillion yen per year after 2025, which is 3 times more than the cost in previous years. Asahi also faced the same internal challenges regarding legacy system, where manual maintenance workflows and limited QA environment have left critical systems outdated and difficult to update. Middleware and OS version have remained unchanged for years, leading to now its nearing end of service life which require huge maintenance cost and effort to continue its operation. To address this problem, we have developed and implemented a Scalable CI/CD Pipeline where isolated development environments can be created and deleted dynamically and is scalable as needed. This Scalable CI/CD Pipeline incorporate GitHub for source code control and branching, Jenkins for pipeline automation, Amazon Web Services for scalable environment, and Docker for environment containerization. This paper presents the design and architecture of the Scalable CI/CD Pipeline, with the implementation along with some use cases. Through Scalable CI/CD, developers can freely and safely test maintenance procedures and do experiments with new technology in their own environment, reducing maintenance cost and drive Digital Transformation (DX). key words: 2025 Japan Cliff, Scalable CI/CD, DevOps, Legacy IT Modernization.