Kill Blue

Juuzou Oogami is a 39-year-old hitman with a perfect record — every target eliminated, no exceptions. Then a mysterious wasp stings him and he wakes up in the body of a 13-year-old. Before he can figure out what happened, his boss hands him a new mission: enroll in a middle school and evaluate whether it's safe enough for the boss's daughter. So now this hardened killer is sitting in a classroom, dealing with homework, hyperactive classmates like Kotatsu Neko-ta, and the principal's daughter Noren Mioka, all while trying not to blow his cover. The comedy writes itself — watching a guy with decades of combat experience navigate the social minefield of middle school is genuinely funny, and the show knows exactly how to play the contrast between his assassin instincts and situations where those instincts are wildly inappropriate. But it's not just jokes. The action scenes hit hard when they show up, and there's a distinctive visual style from Studio Cue that shifts between slick fight choreography and warm, goofy school life moments. If you liked Assassination Classroom's mix of danger and classroom antics, or the way Riddle Story of Devil drops killers into a school setting, this scratches a similar itch. The tone sits somewhere between absurd comedy and genuine action thriller, and based on the manga, it earns both sides of that balance pretty well.