A canonically handsome man. Even Nakajima, the pizza delivery man who attacked Sakamoto's shop, called Nagumo 'handsome.' His appearances throughout the series reveal a man with exceptionally good looks and a solid physique. He generally has a very sly and playful personality, which he displays toward allies and enemies alike. As a killer who stood shoulder-to-shoulder with the legendary Sakamoto Taro, he possesses strength that ranks him 1st or 2nd even among the ORDER. His overwhelming power is evident in his battle against Gaku, a Slur-aligned fighter of ORDER-level strength, whom he eventually defeated. Consequently, Oki, the current leader of the ORDER, seriously considered Nagumo as the next leader. Coming from a family of spies, he is multi-talented in various fields beyond just assassination. His specialty is a level of perfect disguise that borders on supernatural.

A terrifying human weapon formerly known as the 'Legendary Hitman.' Currently, he has retired from the killing business after getting married and enjoys a modest, peaceful life running a small convenience store in the Ikorizaka shopping district on the outskirts of Tokyo. However, whenever his family or daily life is threatened, he unleashes the fearsome combat skills of his hitman days to protect them. He has white hair tied in a bun, wears glasses, is blunt, and is a devoted family man.

Known by the alias X (Slur), he carries the X as his mascot and commits acts of terrorism by killing members of the JAA and its branches. He is the one who placed a bounty on the protagonist, Sakamoto Taro, and is the root of all evil in the story. He was a classmate of Sakamoto and Nagumo during their JCC days. He is a canonically handsome man with white hair. Blunt personality.

He has a chic, cold appearance with silver hair swept back, and red markings around his eyes. His pupils are red, contrasting with the blue eyes of his boss, Uzuki Kei. Like Haruma and Kumanomi, he wears earrings. He usually wears baggy clothes, so it's not very noticeable, but he is shown to be in excellent physical shape when he takes his shirt off. He is a battle maniac who enjoys fighting like a game. However, unlike other talkative or hot-blooded battle maniacs, he is extremely calm and cool-headed during combat. He shows no change in expression even in life-or-death situations and maintains his composure in startling moments. Even outside of combat, he is a man of few words and rarely shows emotion, appearing indifferent to most things. However, he does smile when he encounters a strong opponent.