A combat specialist and member of the Yokohama-based yakuza organization, the Shinjo-gumi. He is also known as "Nagato of the Counter-Technique." He is addressed with honorifics by fellow members Taisei Hirose and Naoji Aki, while Rintaro Ichiai (the presumed No. 3 of the group) speaks to him casually. This suggests a hierarchy of Ichiai > Nagato > Hirose > Aki = Momota. A handsome young man with blonde hair swept to the right, dressed in purple clothing, and wearing a ruby earring in his right ear. He has a habit of trying to guess the names of people he meets for the first time. Standing 174cm tall, his catchphrase is "handsome." Despite his bellicose nature, he is highly aesthetic-conscious, going for hair treatments three times a week. According to the production staff, "He thinks he's handsome, and he actually is." He also reportedly has a strong preference for equality.

A young yakuza belonging to the Amo-gumi, the combat-oriented organization where the protagonist Kabuto Kotoge serves. As of 2022, he is 20 years old. He is a junior member primarily mentored by Kotoge and is considered a promising prospect who will face any job or enemy for the sake of the clan. His birthday is July 3rd. He wears light beige clothing and has short hair of a similar shade. His eyes are orange. Height: 178cm. Well-trained by the Amo-gumi, he has an honest personality filled with a sense of duty (jingi), faithfully carrying out missions for his seniors like Kotoge. Like Kotoge in his younger days, he possesses unbreakable spirit; when captured and interrogated by Shinjiro Nirasawa of the Tennoji-gumi, he refused to talk. Even when recovering from injuries, he has shown the grit to attempt a raid on thugs who hurt him or his comrades.

The yakuza senior who brought Usami into the Amo-gumi. A mid-level yakuza in his late twenties who survives the underworld through sheer effort and grit. It is no exaggeration to say that his behind-the-scenes work supports the Amo-gumi. While often seen as the voice of reason, he is steadily climbing the ladder toward becoming a "madman senior," such as by using a wood plane on villains. His rise through hard work and determination has made him an idol to his juniors. Usami calls him "Kotoge-no-aniki" and speaks to him with deep respect.

A junior member (shatei) of the Shinjo-gumi. His combat skills are decent.