Kill Ao

Thirty-nine-year-old Juuzou Oogami is a legendary hitman who has never failed an assignment. After wiping out a powerful organization, he is stung by a mysterious wasp, collapses, and wakes up in the body of a 13-year-old boy. Before he can understand what happened, his boss gives him a new order: use that body to infiltrate a middle school.

A man who knows almost everything about assassination knows very little about being an ordinary student. Between classmates, homework, and adolescent chaos, Juuzou tries to complete his mission and find a way back to his real body, but the world of killers refuses to leave him alone, and old dangers soon reach his new life.