Tsunayoshi "No-Good Tsuna" Sawada's existence is a disaster. Academic mishaps, physical inadequacy, and a non-existent social circle all contribute to his lack of motivation for attending school. Upon discovering that his love interest, Kyouko Sasagawa, is already taken, Tsuna feels even more disheartened. Little does he know that he is descended from Giotto, the renowned first Vongola.
Reborn, a home tutor claiming to be the greatest hitman in the world, enters the picture. Commissioned by Vongola the Ninth to train Tsuna as the next worthy heir to the Vongola Famiglia, Reborn faces opposition from Tsuna. He adamantly refuses to become a mafia boss, creating tension between the two. Will Reborn coax Tsuna into compliance or use his reluctance to their advantage? This is a tale of an uncertain successor's journey to take on the demanding role of the underworld's next outstanding mafia leader, aided by his companions and an exceptional home tutor.