I have a friend who is thinking about starting a kind of English studio near Shin-Yurigaoka, she has a spare house (nice problem) she has had converted into rooms suitable for acttivies, a large room with a mirrored wall (yoga classes and mom & child things etc...)and various other rooms for English lesson/lectures.
She is looking for people who can teach. I know nothing of pay etc... Just that she is looking people for possibly; Thursday Friday and Saturday... If you want to know more I can put you in touch with her.
PM me for more info.
(I want to point out, this isn't my business and I am not out to financially gain from this. Not that it would make a difference.)