Who Killed Tokuyama Daigoro?

One morning, students find their homeroom teacher Tokuyama Daigoro’s body on the floor of the classroom. A strange school life begins as the students work hard to hide the presence of their teacher's corpse in their classroom. Other teachers from the Academy, their homeroom teacher's wife, his mistress, police, and reporters... One-by-one they visit the classroom and the students face the risk of being discovered. Is it possible to continue to hide it?! And who was it who killed him?!