Erohon G-Men

G-Men is a frequently recurring female character whose job is to check if comic shops' merchandises with adult content are packed and segregated properly. She is a Tokyo Youth Development Counselor and is usually called "G-Men" by the Uma no Hone team, not as a specific name but as an association to her group of porn book agents. In her spare time, G-Men is actually a fan of pornographic books with a special interest in the BL genre.

[Spoiler] It was later on pointed out that she and Sommelier knew each other since elementary, before she move out. It was Sommelier who introduced her to the world of manga in particular with ero and BL genre. [/Spoiler]

(Source: Denki-gai Official Website)