Gary has the task of killing Kyle. He chooses to do this via an injected overdose of illegal drugs, so as to continue the damage even after Kyle's death. (Gary is rather sadistic and evil.) I'm currently teetering between cocaine and heroin.
1) Out of cocaine and heroin, which one is viewed as more of a problem in Japan?
search terms: 'cocaine japan', 'heroin japan', 'cocaine vs heroin japan'. Nothing useful popped up.
2) For either method, how much would be needed to kill Kyle? He's roughly 6' and 160lbs, and has never touched recreational drugs in his life, and is fairly good health. The drugs will be injected during sex, when Kyle climaxes, if that makes any difference.
3) How long would Kyle remain conscious for? Gary is the sort to taunt him as long as he's conscious.
4) What would Gary see happening, as symptoms of the overdose for either drug?
search terms: 'heroin overdose', 'cocaine overdose'. I kept finding things loaded with medical jargon that massively hurt my brain.