If you are a Creative Cloud subscriber you can change in the Creative Cloud Application > Preferences the application install language to any other available. There exits also a Japanese one.
- Leave your US version installed as it is.
- Open preferences in the CC.app and change the app language to Japanese
- Install the Japanese version
- . Switch back the CC.app to US English.
- Launch InDesign
Now will InDesign have installed additionally plugins for Asian Language Support and you will see a different New Document dialog and a lot of other menus and tools supporting Japanese documents.