Reborn is the best hitman of the Vongola crime family, that he also happens to be an infant who still uses a pacifier, and has a pet chameloeon named Leon whose also his partner, and main weapon that lives in his fedora.
Reborn has been sent to Japan to instruct the great-great-great-great grandson of the first Vongola boss, whose family moved to Japan many years before so that the current heir who turns out to be ordinary Japanese high school student Tsunayoshi "Tsuna" Sawada, and completely unprepared to be the new boss of the Vongola family.
Reborn's main method of teaching Tsuna is the "Dying Will Bullet", which is suppose to make the person be "reborn" with a stronger self intent on fulfilling his dying will.
Reborn often disguise himself to camouflage into his surrounding.
Reborn is one of the seven Arcobalenos ( World Strongest Infant Hitmen). He is the Arcobaleno of the sun. He is often considered the strongest Arcobaleno. He often refers to himself as Tsuna's Katekyo Hitman (Home Tutor Hitman). As an Arcobaleno he always remains calm despite how hopeless the situation may appear.