Well they sell e juice at pretty well every don quixote(awesome store by the way they sell everything) . However they are all 0mg as selling nic juices is illegal here. From what I hear you can bring or have 120ml shipped but I haven't done that yet. I believe if they ship it without any nic labels you should be good. As for
vaping in places, pretty much every restaurant/bar has a smoking section. The streets say no smoking pretty much anywhere but smoking areas which sometimes are quite hard to come by. Makes no sense that you can smoke in a bar but when it comes to the streets you can't. From what I have read it is a $20 fine if someone says something but they won't. However in Japan it's more about your reputation then paying fines. Cops are very laid back here. Not sure what else I could say about vaping in japan besides the one shop I went to that only sold vape stuff was .......n expensive so bring your own or buy at don quixote.