My place in an extremely desirable area in Setagaya ku (56m2, 5 mins from Shimokita by foot) is 25man, same size in a equally centrally located part of Suginami ku (Koenji) would be around 15man, bump it out to Mitaka and you’re looking even cheaper, go 10-15 mins from the station instead of 5 and it’s dirt cheap.

I paid 13 man/month for a 47m^2 apartment, and that was in a pretty nice area (Mitaka) and without searching particularly hard.

Our place is two floors, 54 square meters, desirable area, ¥150000/month, within the 23 wards (inside the Yamanote line as well). We started renting it two years ago.

That's weird then, since I know someone in that boat. You can easily get out into Setagaya-ku from Shinjuku with less than a 30 minute commute, and there are plenty of cheap places to live out there