[MSH]

addition to the link: there are multiple locations in Tokyo (see map with locations) where you can hire through the site of WHILL (although no personal experience). But maybe you can contact them and ask what you need to know about hiring and delivering at another location.

My wife just visited Tokyo last week and used a mobility scooter (her own, she can walk short distances, but not more than 100m) and it´s quite easy to go around. Also going in and out the metro was not too difficult, although going to the platforms via lifts was sometimes challenging. All n all finding lifts in general is a challenge, but doable.

No experience with the shinkansen, though.

If you want then I can ask to write you her experience in more detail.