You cannot transfer purchases or subscriptions from one country to another, you have to set them up from the start again.
Generally a country will only have a page in the language that is predominant in that country. You may find that since English is not a language commonly spoken in Japan that places such as the stores are only available in Japanese. (I am surmising that it may not be worth considering adding everything in English for a small number of English speaking residents).
For support information you can override the settings by selecting a different country at the bottom right of a help page. Alternatively, add a line of code forcing the display of a page in another language:
Oubli du mot de passe associé à votre identifiant Apple - Assistance Apple (CH)
I forced that one to Swiss French by adding /fr-ch/ to https://support.apple.com/fr-ch/HT201487
Normally it would default to If you forgot your Apple ID password - Apple Support
since i have my country language set to US English.