One by one, students at Namimori High are being targeted by an unknown gang. It seems that some of those targets are some of Tsuna's friends, and he has to stop the unknown gang before they attack his friends.

After a battle between Gokudera and Chikusa, one of the gang members; Tsuna, Yamamoto, Gokudera, Bianchi, and Reborn set off to capture and defeat the mysterious gang from Kokuyo, only for Yamamoto to run into trouble right off the bat.

After a quick battle between Bianchi and M.M., Haru and Kyoko have been targeted by the serial killer twins Jiji and Didi under Birds' order. Threatening to kill off the girls, Birds plays with Tsuna and his friends, commanding them to beat Tsuna up.

With Tsuna running after Futa, the others are left to deal with the one claiming to be Mukuro himself. He proves to be too much for them in the state they are in, so all hope lies with Tsuna coming back in time. However, even if he does, there is only one Dying Will Bullet left.

With the reveal that their foe wasn't the real Mukuro, everyone breaks into the Kokuyo Middle School building to face the true mastermind. With no Dying Will, Gokudera having to fend off both Chikusa and Ken, and everyone else unconscious, all hope looks lost, but one of Mukuro's captives my prove to be the ace in the hole.

Even after his apparent death, Mukuro still isn't finished as he possesses the bodies of everyone his hit with his trident. There seems to be no way for Tsuna to win with everyone under Mukuro's control and no Dying Will, when Reborn's pet Leon gives off a strange glow.

With the new Rebuke Bullet, Tsuna has reached a new level of power, but it still may not be possible to defeat Mukuro, who still has not revealed his strongest form.