kmj Hello, you can install GrapheneOS on all supported Google Pixel devices, whatever the country, just make sure it's not locked by the operator, so avoid getting it from your mobile operator.
Japanese is available for AOSP (Android Open Source Project), which means that only the parts coming from AOSP will be translated, but not the elements specific to GrapheneOS, which will remain in English. Full translation into several languages for GrapheneOS is planned, but this requires first hiring a professional translator who understands the technical terms correctly.