Aki Hayakawa

A disciplined veteran devil hunter whose family was slaughtered by the Gun Devil, leaving him with a single purpose: revenge. He resents Denji's crudeness and initially tries to drive him out of the job, but gradually becomes something like an older brother to both Denji and Power, sharing an apartment and cooking their meals while quietly shortening his own life with every contract he signs.

Tall and lean with a swordsman's posture, Aki has straight black hair that falls to his jaw in heavy, side-parted bangs, dark narrow eyes and a permanently tired expression. He wears the regulation Public Safety uniform of a black suit, white shirt and loosely knotted tie, usually with a long coat, and keeps a sheathed blade at hand. A cigarette is almost part of the costume. After his contract with the Future Devil, his right eye is marked by a distinctive cross-like sigil, and bandages and fresh bruises accumulate across his face as the series goes on.

Cold on the surface and privately sentimental, Aki treats devil hunting as duty rather than adventure. He is blunt with newcomers, openly threatening to kill Denji at their first meeting, yet he houses and feeds both Denji and Power, cooks for them and enforces household rules with weary patience. Vengeance drives him: he signs away years of his life for weapons that might reach the Gun Devil, and he is honest enough to admit that this is self-destruction. He respects his seniors, protects his juniors, and hides grief behind clipped sentences and smoke. Beneath the stoicism is a man who badly wants the makeshift family he pretends to merely tolerate.

Aki grew up in a snowy northern region with his parents and younger brother. The Gun Devil's rampage killed his family and left him the only survivor, and the memory of that day hardened into a single purpose. He joined the Public Safety Devil Extermination Division to hunt the devil responsible, surviving the brutal attrition rate that kills most recruits within their first years. Assigned to Tokyo Special Division 4, he was partnered with the veteran Himeno, who lost her previous partners and took it upon herself to keep him alive. By the time the story begins he is already an experienced contract holder, trusted by Makima and feared by rookies.

1. Introduction to Public Safety

   Aki meets Denji at the division office and immediately offers to kill him, judging the chainsaw hybrid too dangerous to keep. Ordered by Makima to supervise him instead, he takes Denji into his apartment, then is saddled with Power as well, and finds his disciplined bachelor life turned into a noisy shared household.

2. Bat Devil and the Leech Devil

   While Denji and Power chase the Bat Devil on their own, Aki handles division business and arrives in the aftermath to deal with the fallout. He weighs the pair's recklessness against their results and begins, grudgingly, to treat them as teammates rather than liabilities he has been ordered to babysit.

3. Eternity Devil

   Trapped with his squad in a hotel floor looped by the Eternity Devil, Aki argues against sacrificing anyone, spends days unable to find an exit, and watches Kobeni crack under the pressure. He is forced to accept that Denji's willingness to be mutilated is the fastest path out, and the experience shakes his confidence in control.

4. Katana Man

   The ambush on Division 4 costs Aki nearly everyone he cares about, Himeno most of all. Hospitalised and hollowed out, he trains with Kishibe and then seeks out the Future Devil, accepting a contract that lets him see moments ahead while promising him a wretched death. He returns to the fight and confronts Katana Man directly.

Denji

Reluctant guardian and roommate

Aki threatens to kill him on sight, then houses him, feeds him and nags him about chores. Their rivalry over hot water and dinner slowly turns into something close to brotherhood, which Aki will not admit aloud.

Power

Housemate and subordinate

He treats the Blood Fiend as a feral tenant, scolding her for filth, bad manners and her refusal to bathe, yet he keeps setting a place for her at the table and defends her in the field without hesitation.

Himeno

Senior partner

Himeno trained him, drank with him and made it her mission to keep him breathing. Aki relies on her more than he says, and her sacrifice during the Katana Man ambush breaks something in him that never fully heals.

Makima

Superior officer

Aki follows her orders with disciplined loyalty because she dangles the one thing he wants, a shot at the Gun Devil. He suspects she is using him and obeys anyway, which is precisely her design.

• He greets Denji by drawing a blade and announcing that the hybrid should be put down.
• He gives up years of his life to the Curse Devil in an attempt to stop Katana Man during the ambush on Division 4.
• He breaks down in the hospital corridor after learning what happened to his squad.
• He accepts the Future Devil's contract knowing it guarantees him a miserable end.

• He is a near-constant smoker, a habit shared with his senior Himeno.
• He does the cooking and cleaning in the apartment he shares with Denji and Power.
• His hatred of the Gun Devil is the sole reason he has stayed in Public Safety.
• Devils he contracts with demand very different prices, from body parts to lifespan to the right to watch him die.

• Denji
• Makima
• Power

• Pochita

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