Yes, Japanese people drink a lot, and it is a social issue. But there are a lot of functional alcoholics in Japan.
> Japanese people also are major users of over the counter drugs
Japan is much stricter with medicine than US. Several medicibes that are OTC in US are illegal in Japan: https://jp.usembassy.gov/u-s-citizen-services/local-resource...
I am sure that there are abuse of prescription drugs. But I have not heard anything about a systematic, widespread problem (comparable to prescription drug abuse in US).
A cursory reading of the WP says that the legal status of the drugs you mentioned is more or less the same as the US: