A group of criminals hired by the Hunter Association challenges Gon and his team. Gon and Kurapika win, but Leorio loses time for the team, leaving Killua to save the day with his assassin skills before the clock runs out. Then, the team is left, stranded, on an island for a battle royale.

Gon and Killua split from the group to train at Heavens Arena for six months. However, they are outmatched by another fighter with an ability called Nen. Because Nen is a required skill for Hunters, Gon and Killua vow to learn quickly.

Junior high schooler Tsuna is a failure at just about everything, so imagine his surprise when Reborn, a gun-toting toddler, arrives and informs him that he has come to groom Tsuna to become the future boss of an Italian organized crime family. And he has a bullet with Tsuna's name on it.

"Tsuna is targeted for assassination, so a weapons tuner for the Vongola Family arrives to upgrade Reborn's arsenal. This winds up creating a fair amount of chaos, but it's summer and Tsuna soon finds other distractions-- learning to swim, taking part in a summer poetry contest, plunging into the ocean to rescue a girl in distress, and defying a ghost bent on taking him to the "other side!"--P. [4] of cover.