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.