Something I haven't seen suggested in other comments is to rent a mobile wifi dongle and unlimited internet. This was fantastic when I travelled there since I could get directions and translation in real time through my phone without having to deal with the hassle of roaming charges.

The process to pick it up was super easy - either at the airport or main train station (can't remember which), and returning it was as simple as putting it in the provided mail package and putting it in a mailbox.

Some other things - in my experience Tokyo at least is not super accessible for wheelchairs and the like. I recall that the first subway station I exited from had a two story stair climb with no alternative, and this was hardly a unique experience.

Also, Japan still very much runs on cash. I don't know what it's like for you, but where I am (outside US), we've basically transitioned to a cash-free economy for 90% of transactions so that was a big change for me.