Wilgo provides wheelchair travelers with accessible taxi service from/to Haneda Airport.
https://odekakeoffice.jp/en/

HI, Anita:

Generally speaking, there is no problem in taking public transportations with your powered wheelchair here in Tokyo. You can check the station map of Japan Rail and Tokyo metro at;

https://www.jreast.co.jp/multi/en/stations/
https://www.tokyometro.jp/en/subwaymap/index.html

We are providing wheelchair travelers with wheelchair…

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I guessed so, and sent him a message if he has any solutions.

Wilgo offers accessible taxi services in Tokyo and its vicinities. Our vehicle can accommodate one wheelchair and up to three accompanying. Please check details here at our site.

I recommend you to contact @tak