[wilgo]

Hi,

The voltage here in Japan is 100v and 50 hertz in East part of Japan such as Tokyo.  West part of Japan such as Osaka, Kyoto is 100v and 60 hertz.

A voltage converting unit from 240/230 down to 100V along with an adapter should work,

Check this page for more details.
https://www.accessible-japan.com/voltage-japan-wheelchair-battery-chargers/

Wilgo