Sojun stands 188cm tall, a tan and toned Myumon of the Komainu race born November 23rd. His long, curly blonde hair frames green eyes and a face marked by a beauty spot beneath the left eye. Distinct brown Komainu ears and green dangling earrings adorn his head, while a fluffy tail matches his hair. A tattoo of his emblem marks his upper left arm. His signature attire is a custom-made white tokko-fuku coat with teal lining, silver panels, and multiple straps, featuring a tail slit. Though heavy from holding 69 types of dark equipment, its lining stays soft. Underneath, he wears a black sleeveless turtleneck with side openings, black tapered pants, and slip-on shoes boasting teal soles. He naturally carries a herbal mint scent.

As drummer for DOKONJOFINGER, he commands the "Rolling Twin Max" drums. At Dokonjo North High School, he reigns as the "Damn Contemptible King," Student Council President of the "Despicable Class," known on the streets as "Hell's Guardian Dog." Prideful and self-centered, Sojun relentlessly pursues victory by any means, embracing dirty tactics and dismissing accusations of cowardice. He frequently taunts bandmates, especially calling Hacchin "Hachiko," and actively seeks fights with Joe, whom he deems the strongest. Yet, underlying reliability surfaces when he supports his bandmates. Driven by greed, he constantly hunts money-making opportunities.

Son of a shrine, he is the protective older brother of 919, one year his junior. Sojun deeply cares for him, explicitly hoping 919 will surpass his own strength – the only person he wishes to see exceed him. He savors karaage from Yasu's mother's bento shop and enjoys reading psychology textbooks. He possesses a strong aversion to onions and frequently rides his motorcycle.