Aki Hayakawa

A topknot is Aki's signature, gathering his medium-length black hair atop his head, though untied it spills to his shoulders with long bangs around a pair of blue eyes. He cuts a tall, handsome figure and kept the hair shorter earlier in his career. His standard dress is the Public Safety suit and tie, set off by black earrings, with a sword carried across his back. After the Gun Devil claims his corpse, he becomes the Gun Fiend: loosed hair, dark veins spreading over his brow and eyes, the barrel of an M1911 jutting between them while its hammer pokes out behind his skull, and an M4 carbine where his left forearm used to be.

Beneath a stoic, sometimes bluntly rude exterior, Aki is genuinely tender, quick to grow attached and pained by the suffering of those near him. Himeno calls him a normal person, one who still mourns the dead rather than going numb to loss. His defining drive is vengeance against the Gun Devil for slaughtering his family, a goal he chases relentlessly, yet he repeatedly stakes his own life to shield others even when it derails that mission. He has scant patience for hunters who treat the work lightly or pursue shallow rewards, which fuels his early friction with Denji. Toward devils he can be merciless, deliberately granting them slow deaths, while still showing real warmth to his comrades. That icy front is largely a mask, cracked open when he weeps over Himeno's death. A fear of losing the people he loves haunts him, sharpened by a terrible future the Future Devil shows him. He starts out despising every devil equally, treating them as disposable tools, but slowly bonds with his partners, most strikingly the Angel Devil, for whom he trades two months of his own lifespan and writes a plea to keep him alive.

The Gun Devil's rampage destroys Aki's home in Hokkaido, killing his parents and his younger brother Taiyo, the loss that sets him on the road of revenge. He joins Public Safety and partners first with Himeno, eventually serving under Makima in Special Division 4. Over time he amasses an unusual stack of devil pacts: a tie to the Fox Devil that he forfeits after recklessly summoning it against Katana Man, a deal with the imprisoned Future Devil that lodges the creature in his right eye and grants brief glimpses ahead, and a bond with the Curse Devil that conjures a nail-shaped blade able to inflict grievous harm at the cost of his own lifespan. Tasked by Makima with looking after Denji and Power, he grudgingly takes them in and comes to treat them as family, even petitioning to keep his division clear of the Gun Devil hunt to protect them. During that campaign he is killed and his body is claimed by a fifth of the Gun Devil, reanimating him as the Gun Fiend, who turns on Denji and Power before Denji finally puts him down. In his last moments he pictures the fight as a childhood snowball battle. His final, hollow contract is with Makima as the Control Devil, surrendering his entire being for a power he never gets to wield.