Neko Hai Darake no Toki Naoshi

A locked classroom, barricaded with desks and chairs. In front of him is his own body bound to a chair. The boy realizes that he is dead. This was a mystery novel set in the literature club. Iori Orita, a second-year high school boy, is begged by a stranger, a junior girl, to solve the mystery of the boy's death from the unfinished story — while being restrained to a chair in a classroom, just like in the book. She promises to do anything he wants in return, so he decides to accept her request... The start of a youthful detective drama! (Source: Kadokawa, translated)