It is unknown what methods this woman uses to find the information she is able to give Rin and Mimi but it is always accurate. However, this information does not come cheaply and she doesn't ask for money for her services; she instead demands to be paid in sex acts, either performed with Rin and/or Mimi. As for the latter, Mimi has taken a certain dislike for her (but it hasn't stopped her from asking for information), but Rin usually takes it in stride.
She had a number of ear piercings, as well as a pierced tongue. She also wore rings on all her fingers. She's also fond of drinking grasshoppers; a cocktail made with green creme de menthe (asking for a grasshopper also served as a code word). Rin, however, complains grasshoppers taste like kids' toothpaste.
She was introduced when Rin was searching into whoever injured Professor when she inquired about the whereabouts of a very rare postal stamp, a canceled 1-boo Sutherland stamp. By the time of Episode Four, this informant had long since died, but her partner (Informant's Assistant) had taken her place.