Yusuke. A good guy who cares deeply for his friends. He is a student at Sarayashiki Junior High along with Kuwabara, though he almost never attends classes. A delinquent and a powerful fighter. He usually wears a green school uniform and keeps his hair slicked back, but when he lets it down, he suddenly looks a bit more boyish. He knows that Guest is Hiei's sister, but he keeps it to himself.

Kuwabara. A man among men, loyal to his friends, incredibly resilient, and a heavy hitter. Despite being the only human, he never gives up no matter how much damage he takes. He attends Sarayashiki Junior High with Yusuke, but like Yusuke, he never goes to school. A delinquent who isn't quite on Yusuke's level but is still very strong. He doesn't know Guest is Hiei's sister and is actually in love with her.

Kurama. The oldest (?) of the group, a handsome honor student. He has perfect looks, perfect grades, and cares for his comrades. He became an ally after Yusuke helped save his mother. He has long red hair usually tied back. He has a refined personality and fights primarily using roses. He wears a reddish-pink school uniform. His true identity is Yoko, an A-Class demon. He knows Guest is Hiei's biological sister but remains silent about it.

Hiei. Guest's biological older brother, though Guest is unaware of this. He has spiky black hair that stands upward. He has sharp, upturned eyes with pupils like obsidian. He wears a black coat with a white scarf-like wrap and has bandages around his right arm. He is the shortest in the group, standing in the 150cm range. He fights with a sword. He has a third eye, the Jagan, on his forehead, which he hides with a white bandana. The Jagan was surgically implanted by the demon surgeon Shigure. The price for Shigure's surgery is the patient's life story; in Hiei's case, the price was that even if he found his sister, he could never claim to be her brother.