Japan is largely homogenous and has very harsh drug penalties:
Japan drug law among world’s toughest, personal possession attracts five-year jail https://timesofindia.indiatimes.com/business/international-b...
Why Japan Is So Strict About Drugs https://kotaku.com/why-japan-is-so-strict-about-drugs-183328...
Drug Laws in Japan: You'd Better Have a Prescription https://www.tofugu.com/japan/drug-laws-in-japan/