Ayato Amagiri (天霧綾斗) is the main protagonist of Asterisk War. Ayato's main objective behind entering Seidoukan Academy is to find a purpose in life, though later the latter changes to fighting for Julis.
Ayato's family runs a dojo that teaches ancient techniques by the name of the Amagiri Shinmeiryuu. He grew up with his father and half sister, though his relationship with the former became estranged when the latter disappeared. He also grew up as neighbors with Saya Sasamiya, who played a role as both his childhood friend and later, his sparring partner.
As a kid, he promised to protect his older sister and would even fight with people who would diss or doubt her. Haruka promised to protect him and even put a powerful chain seal on him, so he wouldn't fight with all of his power.