As @tak mentioned, the max weight of the taxi is 250kg

The Whill Model-R that @pao suggested weighs about 57kg.

Your dad’s weight in kg is 136kg, so 136kg + 57kg is 193kg and should be ok.

The only thing is they are a bit expensive.

I know a rental place.

You can use this form:

https://www.accessible-japan.com/renting-wheelchairs-hoists-japan/