Getting around Tokyo in a wheelchair

I'm traveling this May to Shinjuku, it's my first trip to Japan.
I would love to invite my mom as well, but she recently was forced to use a wheelchair. so I wanted to know if it's easy to go around Tokyo with her? Or would it be too crowded for her? I don't want her to feel uncomfortable.
I checked some hotels with facilities for disabled persons, and some websites about train stations. But I'm concerned because Tokyo is very crowded.
Thanks in advance

Tokyo is crowded. Whether on a wheelchair on not, does it matter?

Japanese people are generally polite and if you require the usage of an elevator, they would accomodate.

I don't believe the Japanese people who go out of their way to hassle your mother beacuse she is on a wheelchair. In fact, they would probably give way so as to not get mowed down.

I have no experience with wheelchairs. But i like to mention that i do not think that travelling with the subway or train should not be a problem on non-rush hours. Keep in mind that several stations do not have an escalator/lift getting on/off to platforms. (I found this out travelling with suitcases.)
You need to check this before using a particular station. I believe there is a website giving this info. Maybe somebody can give the url of this website.
Have a nice trip.
B. Slager

This site will be useful for you:
http://www.japan-accessible.com/transport/metro/tokyo.htm

Some/Many stations do not have elevators, some have transforming escalators (so that you can use theme with a wheelchair) but you need staff to operate them.

Sometimes there are elevators but even the staff does not know where the are! :) If you follow the guiding stripes for the blind on the ground you get to the elevators most of the time.

I was in Tokyo for 6 days and do not remember a station that I couldn't use.

Yes Tokyo can be very crowded, but if she is ok with other big cities than Tokyo will not be a problem.

The Tokyo metro buses all have those drop down steps to accommodate disabled. Like the other posters have said some stations don't have elevators in convenient positions, or going right up from the subway to the roadway. It will take some planning. However you could consider 1/2 day or full day tourist bus sightseeing journeys, and they often pick up from major hotels. This way you would only have to contend with one on and one off.

Also, if you're using rail transport and you're using one line only, you can ask the staff to help. They will put a ramp on the car so the wheelchair can be loaded safely and if mention which station you're getting off, the attendant will call ahead to the other station and mention which car you are on, so they can wait for you with another ramp to facilitate your exit.

It gets more complicated when you use lines from different companies. I don't know if they co-ordinate things like this when it's Tokyo Metro and another subway company.

Oh I see! thank you all for your help!
I'll do more research, and again thanks for the links and tips!