Mouryou no Hako: Chuuzenji Atsuko no Jikenbo - Hako no Yurei no Koto

魍魎の匣～特別編　中禅寺敦子の事件簿「箱の幽霊の事」

A side story that reveals the investigative notes that Atsuko, the younger sister of the main character Akihiko Chuzenji, wrote about the brutal dismembering incidents in the main story. (Source: ANN)