Kashiwagi, Ryoko

A woman who resembles Reira, Shin seems to spend a great deal of time with her and she seems to favour sleeping with much younger men. When Shin first arrived in Tokyo, Ryoko took him under her wing and taught him about the adult world as well as how to get money from women. Shin came to view her as a foster mother of sorts and remarks that she does not resemble Reira as closely as he originally thought.

[Spoiler] She is eventually arrested along with Shin for the possession of marijuana. [/Spoiler]

(Source: Wikipedia)