A new Fujitsu designed powerful Arm general purpose CPU will be presented. It supports Armv8-A and 512-bit SVE, scalable vector extension, ensuring binary compatibility amongst other Arm processors. It also provides superior memory bandwidth for real application performance by utilizing the on-package stacked memories. The CPU realizes the scalable energy efficient system since it is implemented as a system-on-a-chip integrating the interconnect, known as TofuD. The post-K featuring the CPU is under developing with RIKEN targeting the hundredfold of application performance of the K computer. The system also maintains binary compatibility standards, such as SBSA, SBBR, which contributes to complement and accelerate Arm ecosystem prosperity supporting of system software development including optimizing compilers, libraries, and tools. In the presentation, preliminary performance evaluation results and Fujitsu’s activities for prosperity of the Arm HPC ecosystem will be also discussed.