for God's sake don't do anything that can get you put in jail. It can be a hell of waiting for no good reason for gajin, even ones that speak the language.
Prison in Japan: Part 1 “The Taxi Ride” | Japan: Stippy
He's in bars because thats what you do. Over there they take a very different approach to stuff like hanging out in bars & drinking, its a very common night out. don't know about his employment situation but sometimes you are practically expected to go out drinking with your boss/coworkers.