Maybe @wanping knows a bit more, but according to this you can watch the yumomi in a wheelchair:

https://www.kusatsu-onsen.ne.jp/netsunoyu/0001.html

Not a lot of detail! So might want to contact them directly.

This blog also mentions going and there were no steps and the staff were kind.

https://www.z-z.jp/thbbs.cgi?id=kokofurig&p3=&th=119

This might help: https://help.flynorse.com/articles/special-assistance/travelling-with-a-wheelchair/6266a08e0c103b24added742

Ramen can be difficult.. you may want to try Ramen Street in Tokyo Station.

Asakusa is famous for soba and tempura, you should check out Akimitsu, I’ve been there twice in my power wheelchair:

https://maps.app.goo.gl/WtpLjduM7khZXAq97

If the weather is nice, eating on the street seating areas of Hoppy Dori is fun too.

We can certainly look!

How far from the station can you go? What type of food? What are your specific needs?