Japan Sex Guide advises where to find sex , working girls , prostitution , street hookers , brothels , red-light districts , sex shops , prostitutes , erotic massage parlors , strip clubs and escorts in Japan , Asia. Prostitution is illegal in Japan. However, enforcement is lax, and the law specifically defines prostitution as "sex in exchange for money". In other words, if you pay for some other "service" and proceed to have sex by "private agreement," the law does not recognize it as prostitution. As such, Japan still has one of the most vibrant sex industries in the world.