Si Xing Long is one of the seven Shadow Dragons, the fifth to be fought by Gokuu and Pan. He is the dragon of the Four-Star Dragon Ball, and is the twin brother of San Xing Long. He represents the element of fire. He was born from King Piccolo wishing for the restoration of his youth during the events of the original Dragon Ball series. His name refers to a nova, an exploding sun, referencing his incredible fire powers. Si Xing Long is very faithful to his fellow Shadow Dragons, but also is fair to his enemies in battle, never resorting to desperate tactics, no matter what situation he is in. He will even assist his enemies if he considers his brothers' tactics on them unfair and desperate. He is also one of the most serious dragons, rarely smiling and limiting his taunts to the heat of battle. Si Xing Long's innate nobility and morals, unique among the seven Shadow Dragons, could stem from a number of places. The most obvious is that he is the dragon of the Four-Star ball, a Dragon Ball which has always been associated with Gokuu and his adopted grandfather, Grandpa Gohan. In his true form Si Xing Long is one of the strongest Shadow Dragons, behind only Yi Xing Long. Unlike most of his fellow Shadow Dragons, he is proficient in martial arts, allowing him to pose a great threat with or without his devastating elemental powers. Si Xing Long's abilities are all heat based. He can raise his temperature to more than 6,000 degrees Celsius, effectively making him hotter than the surface of the Sun. (Source: Dragon Ball Wiki)