The first informant is introduced in episode two and is mentioned to have died prior to episode four. The second informant is introduced as an assistant of the first one in episode three and inherits her position in the next episode. In return for their services, both demand lesbian sex with either Rin or Mimi. Mimi is extremely uncomfortable and unnerved by this at first but seems to have entered into some sort of relationship with the second informant by episode four. In episode six, the second informant is apparently dead as well, replaced by a third one, with whom Mimi keeps a strictly professional relationship.
In episode 3 during their search for information on Rin, Kouki Maeno was forced to watch the informants have sex with Mimi or else no information would be given.