Found this site that ranks neighborhoods around Tokyo stations according to a few factors, the most interesting being "depravity." You can set your desired depravity score, and ekirate.com will map the most depraved neighborhoods.
1. Is that map totally missing YYoshiwara?
2. Nakano has fureai-doori which has kyaba but it is by no means a fuuzoku paradise. Even Kichijouji has a soapland.
3. Ikebukuro needs a few more markers; its just as bad as Gotanda IMO.