Yoichi Nagumo

Tall and slim yet clearly built for a fight, Nagumo draws the eye with large dark eyes and black hair kept at medium length. His usual outfit leans on a patterned red polo beneath a cream trench coat, finished with navy trousers, though he trades it for a black business suit with a white shirt and tie when the moment calls for something formal. A gray briefcase rides on his back, holding the multi-purpose blade he fights with. His frame has barely changed since his mid-teens, a point Kindaka remarked on after waking from an eight-year coma, though his tattoos have multiplied over time. That ink circles heavily around the golden ratio, from a Fibonacci spiral inked on his neck to nested-root formulas running down his forearm, alongside further designs nodding to art, philosophy, and mathematics.

An ever-present smile and an easy, unbothered manner define Nagumo, along with a gift for irritating those around him until they want him dead. He tosses out dark little jokes, speaks in a lilting singsong when he toys with a foe, and stays carefree even mid-battle, once handing Minimalist a set of dice to pick which blade would kill him. Beneath the clowning sits a colder operator who chases his own agenda and will cross ethical lines for a result, blackmailing Satoru Yotsumura and threatening his son, or taking part in a kidnapping to pry loose information. He holds that killing carries no built-in good or evil, yet judges an overzealous sense of justice as the worse sin, and though he claims to loathe deception he leans on it as the true key to killing.

His real warmth surfaces around the people he loves. He and Sakamoto have been friends since their teens at the JCC, and he keeps that bond alive even after Sakamoto retires and becomes a target, once disguising him as his wife Aoi to handle a threat. His ties to Rion Akao run just as deep, formed when he crossed from the spy track into the assassin department, and the two joined Sakamoto to become an inseparable, destructive trio whose antics got them expelled and steered toward the Order through Kindaka. After Rion's death he poured effort into investigating it, covering eight years of Kindaka's hospital bills before presenting the recovered man with the full total. He needled Hyo more than anyone in the Order yet mourned his passing, firing a shot skyward in tribute.

As a onetime member of the Order, Nagumo ranks among the strongest assassins in the country. He was hailed as one of three exceptional prospects to pass through the JCC alongside Sakamoto and Rion, and Slur pegged him as one of the Order's top two fighters, making him effectively the second strongest killer under the JAA banner. Granny Miya judged him stronger than Sakamoto after the latter's long retirement, and Kashima marked him as an S-rank threat. His mastery of disguise lets him copy another person's look in an instant and even reshape someone else's body, though his handiwork on others lasts only a day. In close combat he wields blades with lethal precision, once decapitating Minimalist in a flash and later grinding down the far more powerful Gaku through pure skill and trickery.

His talents reach well past swordplay. He can knock a man out with killing intent alone, ranked fourth among the JCC's greatest marksmen, signals allies in Morse code, and reads situations with a spy's sharp mind, quickly sniffing out the mole Erio Muto. Speed, strength, reflexes, and durability all sit far above the ordinary, letting him shrug off blows that hurl him through walls. His signature tool is the six-function Rokutoku knife, a folding multi-weapon he cycles through in battle, supplemented by hidden daggers, a scythe, an axe, chains, a smokescreen, a nearly invisible ceramic blade, and a die he rolls to pick a killing method or bait an opponent into a fatal opening.