Volunteering in Yokohama / Tokyo with the Homeless / Elderly

Hello, all.

I am looking for opportunities to volunteer with the homeless or elderly in either Tokyo or Yokohama.

I live and work in Yokohama, so that is the preferred, but I don't mind commuting to Tokyo.

Does anyone have an websites or recommendations that can point me in the right direction?

I speak Japanese fluently, so I have no issues with organizations / sites 100% in Japanese.

Thanks in advance.