Sodachi Oikura (老倉 育, Oikura Sodachi) is a third year student of Naoetsu Private High School and childhood friend of Koyomi Araragi, having studied in the same class as him two years before the events of the class meeting, in which she and Koyomi determine who is the culprit of a crime. Sodachi is the titular protagonist of three arcs: Sodachi Riddle, Sodachi Lost, and Sodachi Fiasco.