Junior high student Tsuna is a failure at school, sports and socializing. But when toddler assassin Reborn arrives to groom Tsuna for his future as a Mafia boss, Tsuna may have found the „magic bullet” he needs to turn his life around!
Tsuna faces a group of assassins that's taken exception to his candidacy for the coveted position of boss of the Vongola Family. With recent experience having made their deficiencies in fighting prowess glaringly apparent, Tsuna's „family” members decide they need to undergo a serious training regimen in order to meet this new threat. It hardly helps that Tsuna, now possessed of an impressive new ability, needs the training more than anyone else!