Who Killed Daigoro Tokuyama? S01 E05 I Want To Judge

The students find something hidden in the air-conditioner. Was it their homeroom teacher, Daigoro Tokuyama who hid it? As the students investigate, Detective Yashiro suddenly returns. The next day, the classroom is hot, and the body is reeking. That's when Neru Nagahama suddenly comes back to school. They interrogate her the moment the teacher leaves the room.