[Nyororin]

I would invest in a one-handed folding stroller. Most strollers in Japan can fold down very quickly to an extremely compact size. I have never encountered a problem using a stroller on the train, I just fold it up if there are a lot of people.

I can`t really think of any situations that it would need to be avoided, other than obvious ones (no pavement, tons of stairs and no elevators, etc). It always just ends up being an issue of folding the stroller in tight spaces. If you are using a foreign made stroller, that might not be possible - which is why I recommend investing in a Japanese one.