Nobuto Nakajō is a 22-year-old male born March 23, 1977, standing 183 cm tall with blood type B and black hair typically covering his eyes. He resides in Chiba prefecture. As the third son and heir to a serious illness hospital, he originates from a medical family. His delinquent behavior, propensity for violence, and willingness to shed others' blood caused legal disownment and departure from medical school.

Prior gang involvement led to his high school expulsion, granting street fighting skills and theft training. He maintains a pragmatic, nihilistic worldview yet exhibits strong self-confidence and a capacity to care for others. Within Team AAA, he assumes leadership due to age and experience. His combat style emphasizes brawling over grappling, deploying violence without hesitation.

Nobuto works multiple jobs: manual laborer at a day labor place, shogi classroom lecturer, and guard. He inhabits a small apartment frequented by different women. His hobbies include cooking and strategy games, alongside heavy smoking and alcohol consumption.

Initially distrusting teammates Kazuo Saitoh and Toki Mishiba, he openly considered abandoning Team AAA for better opportunities. Despite this pragmatic self-interest, he gradually developed protective instincts—particularly toward Kazuo, whom he initially dismissed as incompetent—intervening to assist him in dangerous situations.