|Family||Yuuma Amaterasu (Younger Brother)|
|Devil Fruit||Jishaku Jishaku no Mi|
Seiya Amaterasu (星矢天照, Starry Light In A Shining Heaven)
Seiya at first appears to be come of as a very violent person to those around him, a trait that seems to have been with him since his younger days. He comes across as cold, stoic, and arrogant, even to his friends. In battle Seiya will do anything to win, much to the chagrin of his allies, especially Linyin. People tend to think that he looks down on those that are weaker than him, given by the fact that he often refer to them as though they were nothing but weeds and that he has no problem with attacking people from behind. When speaking to people he has yet to associate himself with, Seiya describes himself as both serious and solitary. He keeps this facade up in order to prevent people from becoming too close to him and getting hurt. Going along with this, he claims he has no friends and does not desire them. Despite his claims to not care for anyone, it seems that he tends to rapidly develop feelings for people that he meets.
However, once one gets past this act Seiya is normally a very cheerful person to be around, even becoming completely helpless and incompetent when against the face of a pretty girl. However, he has been shown to have a dark side and is brutally tactless when he wants be. Such as when he once allowed a fellow pirate to be captured and killed by the marines, after said unnamed pirate insulted Seiya and Yuuma just moments earlier. He has a knack for finding clandestine information with ease, knowing about most things that would seem to be vague details, and is unusually perceptive. When a conflict is unfolding that doesn't involve him, he prefers remaining on the sidelines observing and is extraordinarily capable of removing himself from any incoming danger.
When he finally opens up to people, Seiya is cheerful, yet laid back, is compassionate to others, and has a chronic tardiness problem. Although at times Seiya tends to push everyone away, though he means well.
His naturally calm attitude is used to his advantage in battle, as it is easier for him to maintain his composure to stay focused on the situation at hand and ultimately notice everything around him. Through this, he can make keen and thought-out decisions allowing him to stay steps ahead of his opponents. Despite his strong belief in cherishing and protected loved ones, Seiya's personal life is almost non-existent because of the persona he initially displays.
Though generally seen as a laid-back, jovial fellow, this side of Seiya is deceptively different from his cunning and serious side of his personality, when the situation warrants it. Despite his carefree attitude, his speech is always polite, though it is sometimes sarcastic.
Gauntlets: These gauntlets were crafted by Seiya and Yuuma's father and act as a focus for his devil fruit abilities. They are black metallic gauntlets that go up to his shoulder in length, with a red jewel like emblem inscribed onto the back of his hands. When in use roman numerals rotate around him, which are black with a slight orange aura emanating from them and small black electrical discharges start eminating from them signaling that the Jishaku Jishaku no Mi is ready for use.