[schroth-sensei]

Hello Julia,
If you’re getting around by trains, I’d just stick to using a motorized wheelchair because it is so easy to use the trains (the train rides are so smooth, I used them nearly every day of my trips). I recently stayed in Yokohama for a 90-day stay, I brought my motorized wheelchair and as Josh said it was nice to have it for hilly areas. Sidewalks and station access wasn’t an issue either for my big motorized wheelchair (some subway elevators were tight, but worked). For the areas trains don’t quite reach, you should be able to get around using city buses without any real issues as well (I only had to use them a handful of times).
As for restaurants and shops, no doubt there are those that are not accessible because of steps or even very skinny hallways. I wouldn’t count on it to be a 1-step-outside-only issue either, if the outside isn’t accessible then chances are the inside may have additional challenges no matter the wheelchair you use. I don’t recommend being dead-set on going to a particular place without a little accessibility research beforehand (Google street view helps a lot). However, in a place like Tokyo, you usually don’t have to go far to find a store/restaurant selling virtually the same things that may also be accessible. In this case, newer malls/department stores are a good spot to find accessible options, especially for dining options where food courts or entire floors are full of restaurants.