Mystery of the Rainbow Arrives! is the fortieth volume of the Katekyo Hitman Reborn! series.
- Chapter 382: The Power of the Vindice (
復讐者の力, Vindiche no chikara?)
- Chapter 383: Flames of Determination (決意の炎, Ketsui no honō?)
- Chapter 384: Those Who Watch The Battle (戦いを見る者, Tatakai o miru mono?)
- Chapter 385: Invitation (勧誘, Kan'yū?)
- Chapter 386: The Fated Day and the Representative War (運命の日と代理戦争, Unmei no hi to dairi sensō?)
- Chapter 387: Reborn's Concern (リボーンの疑問, Ribōn no gimon?)
- Chapter 388: Dilemma (窮地, Kyūchi?)
- Chapter 389: Tsuna Moves (ツナ動く, Tsuna ugoku?)
- Chapter 390: Home Tutor Disqualification (家庭教師失格, Katekyō shikkaku?)
- Chapter 391: Grand Convention (大召集, Dai shōshū?)
Upon witnessing the Vindice's true form, the allied Team Verde and Reborn continue to battle it out. Realizing that the Vindice had become much stronger than before. they decide to use a different tactic; Mukuro decides to finish them off alone while Tsuna is distracting them and unleashes Genjū Gagaia. However, unlike before, the attacks are ineffective on the Vindice and the crows from Mukuro's technique are destroyed by the Vindice's chains. Realizing that they were overwhelmed, both teams started to lose hope, until Chrome appears and lends her power to Mukuro for a powerful Genjū Mugaia attack, destroying 2 enemies' Rainbow Wristwatches in the process. Tsuna then goes on to battle Jaque, but Reborn notices that Tsuna was holding back. To ensure that Tsuna's boss watch would remain undamaged, Reborn convinces him to go all out. Tsuna then defeats Jaque. Bermuda then appears to offer Reborn to join his team, but the latter declines. Bermuda then creates a warp hole that sucks Reborn in, while Tsuna follows after Reborn.
Rebron tells Tsuna he let himself be taken in order to discover the secrets that Bermuda was keeping. Tsuna and Reborn then ascertain the reasoning for the existence of the Arcobaleno and the true purpose behind the Representative Battle of the Rainbow. Bermuda asks Reborn for assistance to kill Checker Face. Returning to Namimori after a heated discusion, Reborn goes off to inform the other Arcobaleno of the situation, leaving Tsuna to reflect on everything that just happened. After some contemplation, he decides to call Timoteo in order to get into contact with Talbot. Tsuna then sets out to find the other representatives to form a team to overpower Team Bermuda.