Mental health has become far too medicalised in the west in the interest of multiple large entities (including but not limited to the pharma mafia), so your vision of Japan might be influenced by your standards for mental health.
Worth pointing out is that the mental health issues are only the symptom and not the cause, the cause should be adressed first rather than the symptoms.
Treatment for mental health involves more than just medication, for any program worth its salt. My current treatment includes weekly group therapy, weekly individual therapy, and weekly mindfulness class, in addition to medication. All of this together has completely changed my life over the past six months, to the point I'm actually about to be able to seek employment in programming again (sincere thanks for the fantastic healthcare for people in poverty, Massachusetts!).
Too medicalized compared to what? Is there strong evidence of other approaches delivering superior outcomes on a cost adjusted basis? I know CBT has been shown to work well for some patients with some conditions, but it isn't effective for everyone.
How do you determine the root causes to be addressed?
As an example, maybe instead of giving kids speed so they can concentrate we might admit that being forced to sit in a room all day with less and less recess is actually quite boring.
You could say some mental health issues are symptoms of underlying social/cultural issues. Since the latter are difficult to diagnose and heal, it's up to the individuals to cope and adapt to the "sick" mental environment.
Worth pointing out is that the mental health issues are only the symptom and not the cause, the cause should be adressed first rather than the symptoms.