Reborn (Hitman Reborn!)

Reborn (リボーン, Ribōn) is the eponymous character of the series, the infant home tutor of Tsuna, Dino's former tutor and the world's strongest hitman. Before he received the Arcobaleno Curse, he greeted people with the word "Chaos". However, he says "Ciaossu" while he is in his cursed form due to his undeveloped vocal cords as a five-years-old. "Ciaossu", incidentally, is a portmanteau of the Italian and Japanese greetings "Ciao" and "Ossu".