Hakkai is a teenager of above-average height with royal blue hair styled in a crew cut. A swirl design is shaved on the left side of his head, extending to the back of his head. His eyes are an indigo color, and he has a noticeable scar on the left side of his lip. He wears a concentric teardrop earring on his left ear. Hakkai is shown to be a timid but friendly guy. When it comes to his personality he is nothing like his older brother Taiju who is disciplined and bloodlusted. Hakkai showed a lot of care and compassion to his sister and to his friends, he was even willing to take the blame for the murder of Taiju so that Yuzuha didn't have to suffer the consequences. Hakkai also gave up the comfort of being in Toman in order to help Takemichi escape from Black Dragon. He is very old fashioned when it comes to his mannerisms and honor, feeling as if he owes Takemichi his life by calling him "Onjin" which translates to "A person who you owe your life too."