If it's a prompt pop up saying japan only, you can use a tool (no regionloader) or a cracked exe to make the game believe you're in japan. Most sharing site share the tool / crack after a few day if not day one.
If it require japanese local setting, the only way is to use local setting emulating tool like Local Emulator.
But emulating tool don't always work, and they can make the use of translating tool difficult.