Katekyo Hitman Reborn!

At Mafia Island, Tsuna fails to prove his identity as the Vongola Family's 10th boss, and is transported to the back of the island where he is given a new chance to prove himself. There, he meets another Arcobaleno, Colonello. Colonello and Reborn put Tsuna through tough training. Meanwhile, another Arcobaleno invades the island with an army.