The Explosion Club - Box (1-3)

Three years have passed since a high school student, victim of bullying and indifference from his classmates, blew himself up in his classroom in a suicide bombing. Now, the seven surviving students have gathered in the classroom where they had glimpsed hell, on the initiative of one of them, Takumi Shindo, who since the day of the tragedy has dedicated himself to investigating who supplied the explosive to his would-be executioner... A search that led him to a dramatic and unexpected conclusion!