Knuckle

Weapon: Knuckle of Maximum Break
Flame: Sun

Known as the Vongola Primo's Sun Guardian, as well as an undefeated boxing champion. Due to his sheer strength, he accidentally killed an opponent during a match and soon after dedicated his life to God. At his Family's moment of crisis, however, he gave himself 3 minutes to fight and managed to save his friends when they truly needed him. The First Sun Guardian and Ryohei, Vongola Decimo's Sun Guardian, have a strong resemblance in their Weapon of choice, their way of fighting and their physical features. According to Lussuria, he was able to break lights with the pressure of his punches. (Source: Reborn Wikia)