My family has a simple apartment in the outskirts of Tokyo, and we've occasionally toyed with the idea of renting it to foreigners for for cheapish (~$400/mo). If you don't go too crazy with fancy dining or anything like that, then I think living in Tokyo for ~$600 / mo isn't an insane proposition. Here's the website we created if you're interested - https://mitakahouse.omardiab.com/