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!

Tsuna and his friends continue to train for the imminent confrontation with the Varia. Tsuna manages to complete the second stage of his training and Yamamoto has learned all he can from his father about swordplay, but Gokudera has yet to master the fighting technique of Dr. Shamal. Meanwhile, two members of the Varia have arrived ahead of schedule and are looking to take out anyone in possession of a Vongola ring!

The battle between the Varia assassins and Tsuna's "family" for the Vongola rings is on! Tsuna's intervention on Lambo's behalf has caused forfeiture of both their rings, so it's up to Gokudera to hold up the side. He gives it his all, but the Varia are proving themselves masters of not playing fair and appear to view the rules, such as they are, as applicable only to their opponents!

Yamamoto uses the Shigure Soen Ryu sword technique taught to him by his father to battle Superbi Squalo, who has beaten a Shigure Soen Ryu practitioner once before! Even though Squalo sees through his moves, Yamamoto refuses to lose faith in the technique and presses on. The question is, does he have any chance of winning?! Meanwhile, the identity of the person chosen to be Tsuna's Mist Guardian is finally revealed!

Tsuna's old adversary, Mukuro Rokudo, has successfully fought on the side of Tsuna's "family" for possession of the Mist Ring. But his opponent, the Varia known as Mammon, has a highly developed sense of never-say-die! Later, Tsuna finally completes his training and returns in time to confront one of the Varia who is running amok. The whole game changes, however, when he finds out who this Varia really is!

Tsuna finally faces Xanxus in the Ring battle! While they trade blows, Xanxus shows off the power of his Flames of Rage, the very ability possessed by the 2nd Generation boss of the Vongola. Tsuna soon discovers that Xanxus has brought a lot more to the party and is pummeled by attack after attack. Tsuna's friends, meanwhile, pass the Storm Ring around in an attempt to protect Lambo from the renewed fury of Leviathan!

Reborn has set his sights on a new recruit for the Vongola Famiglia and prepares a rigorous initiation rite. But when deadly beauty Bianchi fixes Reborn in her romantic crosshairs and swears to kill anyone who stands in the way of their impending romance, it's Tsuna whose life is in danger!

Tsuna is chosen to lead his team in the main event of the school festival, the Bodaoshi, an anything-goes competition where three teams try to knock down their opponents' "general" from a tall pole. But things get complicated when Tsuna's team is accused of cheating, and the other two teams form an alliance!

It's a reunion - mafia style! Dino, the 10th-generation boss of the Chiavorone family and Reborn's former student, brings his squad of goons to pay Tsuna a visit. The explosive little Lambo decides to liven things up a bit by tossing several grenades at the goons. Things quickly escalate as Dino springs into action in a battle of whips versus grenades!

Tsuna becomes the protector of a master statistician and his book of statistics, which supposedly holds the key to Mafia control of the world! Naturally, other gangs would like to have this book, but that isn't Tsuna's biggest challenge. He also gets embroiled in the snowball fight to end all snowball fights, and finds himself on a zoo date with Kyoko!

As if Reborn's training regimen at home and at school weren't harrowing enough, Tsuna soon discovers that even his vacations are now being co-opted by his "tutor" to further the cause of turning Tsuna into a proper boss for the Vongola Family! But even his leisure travails pale when he finds out what awaits at the wedding of Reborn and Bianchi!

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"!