I was reading about a voice actress arrested for cocaine use, and it occurred to me that I have no knowledge of how the current state of Japanese drug laws came to be. This question is very general I understand, but there is a lot to know, I'm sure. When were various specific drugs banned, and under what contexts? What was the attitude toward these substances before prohibition?
Thank you in advance to anyone who brings any knowledge on this subject. I will gladly read any source material presented to come to a better understanding of the matter.
Finding legitimate sources in English on this is a pain, but I was able to find this old UN paper on the question.
Essentially, Opium prohibition has been around in Japan for a long time--since before the Meiji Restoration--and was strictly controlled through the prewar period. There are also prohibitions on opium use from before then but they wouldn't be 'laws' in the same sense. Japan's other drug laws--there are three of them, concerning stimulants, narcotics, and pot, all date from during the US Occupation and shortly after. Pot and narcotic availability here is blamed on the presence of US soldiers. Amphetamines, which were actually invented in Japan and widely distributed during the war to increase industrial productivity, etc. are a different story.
The running assertion in this paper is that with some exceptions, most drugs in Japan have been banned more or less ever since they have been available. Addiction to philopon, the trade name for methamphetamine in Japan, is a pretty common feature of accounts of immediate postwar Japan and there was pretty obviously a relationship between its wartime distribution and abuse during the occupation, especially since there was a 2 1/2 year window where it was legal. But the unifying explanation for all of these said drug laws is basically as a response to post-WWII social anomie, of which drugs were a part.