Houkago

Someone is trying to kill Maejima, the unassuming archery club coach and math teacher at Seika Women's High School. Pure luck has gotten him through several attempts, but he has no idea who's behind it, and the school principal would rather not involve the police in what's surely just a student acting out. With the entire faculty and students as suspects, will Maejima figure out who's responsible before his luck runs out? (Source: Storm in Heaven)