Yakushiji Ryouko no Kaiki Jikenbo is adapted from a series of light novels written by Tanaka Yoshiki and illustrated by Kakinouchi Narumi. The story follows 27‑year‑old multilingual investigator Ryouko Yakushiji, a graduate of Tokyo University’s elite Department of Law, as she tackles bizarre and supernatural cases while working for the Tokyo Metropolitan Police. Alongside her investigations, Ryouko competes with her equally skilled and striking rival, detective Yukiko Muromachi.