One thing to bear in mind about Japan: they put people in mental institutions rather than jails. All it takes to get a person committed against their will is the opinion of one family member and one psychiatrist. In the US, a court order is needed to hold someone against their will for longer than a few days.
Generally speaking, "troublemakers" will go to a mental hospital before going to jail. That's probably why suicides are so high in Japan as well: the mental health system is so overloaded they can't appropriately deal with real problems.