Kara no Shoujo

Reiji is a private detective. One day, he receives a strange offer from a girl, "Please look for... me. True me." At that time, a series of abnormal murder cases happen and Reiji is offered to investigate it as well. There is a girls high school Yukari, Reijis younger sister, goes and two female students are missing. Tokio, vice principal of the school, offers Reiji to search for them. As a result, Reiji receives three offers at the same time. To collect information, he starts working at the school in disguise and meets Toko, who asked him to look for real her before.