About 75% of all cosplayers are women so stores cater to that demographic. Cospa and ACOS usually carry a reasonable amount of male costumes and Jupiter has a few racks of male costumes (you just might have to search for them).
ACOS in Ikebukuro usually has a large selection of men's costumes on hand. Also, check Cospa and Acos's catalogs. They might have the male costume you are looking for, just not on display at the store.
Edit: Oh and check out K-Books Ikebukuro. They carry a lot of male costumes on hand now that I think about it.
Last edited by Tsumanne : 12-19-2012 at 06:46 PM.