Ryoko's Case File

 Based on a series of light novels written by Tanaka Yoshiki and illustrated by Kakinouchi Narumi.

The story revolves around Ryouko Yakushiji, a 27-year-old multilingual investigator that graduated from Tokyo University's elite Department of Law, and the bizarre cases she faces while working for the Tokyo Metropolitan Police. Yakushiji not only has to deal with supernatural beings in her line of work, but also her rival Yukiko Muromachi, another equally talented and beautiful police investigator.

(Source: AniDB)