@edwardlou that depend on what part of japan they are, since lowest age for it to be considered that is 12 or younger, some prefectures change it to between 16-18, and while he may be an adult at 18 in some countries, he is not really considered an adult in japan until 20 (i think it changed to 18 because voting, but not sure if the other law did too, since for some stuff you still need to be 20+)
this topic is really getting annoying tbh