I just read the article about where to buy new bicycles in Tokyo, and wanted to comment on the advice: “Don’t leave your bicycle anywhere”. I’m not sure if that means “Don’t leave your bike just anywhere” or literally “Don’t leave it anywhere”. But in either case, I don’t agree.
I’ve been living (and cycling) in Tokyo for over 20 years, and can say, quite confidently, that if you use your common sense, you can leave it pretty much anywhere. Obviously not right in front of a station entrance, where it might get taken away (not by men in green uniforms, whose job - in central Tokyo anyway - is to deal with illegally parked cars), but in trucks sent by the local ward office on sporadic occasions. Looking where other people leave bikes is a pretty good guide, and, by a trial and error system, you can find other good places. If you leave a bike somewhere on a number of occasions for several hours without it getting a ticket, it’s likely to be safe.
I can recommend several places in Hiroo, for example, within a minute’s walk of the station, where I’ve left my bike on numerous occasions with no problem, even overnight. Like many things in Japan, the bicycle parking system is very regulated. The people - often stationed near major stations (they have blue and grey uniforms, clearly marked) - have their patrol routes and don’t go beyond them.