Aki Hayakawa

Aki had a crush on Makima and seemed to trust her deeply, although this was a result of Makima's powers of control. This would explain why Aki could not recall his reason for liking her. Makima had an utter disregard for Aki's feelings and was not interested in him beyond his use as a tool. She frequently dumped responsibility on him, like having him take in Power and Denji without asking first and manipulating him when he protested.

After being partnered up, the two started out on a rough patch with both of them being unable to get along with each other. Despite this, they began to warm up to each other, even to the point where they cared about each other's well-being, shown when Aki was willing to hold the Angel Devil's hand in order to save him, despite knowing that in doing so, his lifespan would be shortened. Furthermore, the Angel Devil was inclined to inform Aki of untold information such as the life cycle of Devils. Following the encounter with the Darkness Devil, Aki worried for the Angel Devil's life, suggesting him to form contracts with Devil Hunters in order to avoid extermination. The Angel Devil also asked Aki what he sees in Makima since it's shown he liked her, and Aki doesn't know the answer. Much like Himeno, he also told Aki to quit the division and get another job before he gets killed.

Aki and Power also had a less than positive relationship at the beginning, although perhaps not so much as with Denji. Aki disliked Power's vulgar and ungrateful attitude and found her extremely obnoxious. He also took in Power when Makima requested it and the two gradually warmed up to each other. While he seemed embarrassed and annoyed by Power's constant escapades, he considered her a friend as well. Protecting Power was another reason why he wanted the Fourth Division to withdraw from fighting the Gun Devil.

Aki had known Himeno since joining Public Safety and she was his first work partner. She was the one responsible for getting him into smoking and she also attempted to get him to quit his job in order to ensure his safety.

Himeno had a crush on Aki and it was implied that she kissed him when he was a new recruit. Although it seems that Aki did not return her feelings, he did consider Himeno a dear friend and cried in the wake of her death.

Aki and Denji initially hated one another with their first mission ending up in a physical and verbal altercation, wherein Aki insults and punches Denji, only for Denji to knee him in the crotch and kick him while he's down. He thinks Denji is a simpleton, brutish, vulgar and too unthinking to continue in a dangerous line of work. Despite the fight, they continued to work together due to Makima's request. Also at Makima's request, Aki allowed Denji to move into his home and took care of him. After fighting alongside each other and living in the same household, Aki began to consider Denji a close friend, although he still found him obnoxious at times. He even went so far as to request the Fourth Division be exempt from fighting the Gun Devil in an attempt to keep Denji and Power safe.

Aki generally appears to be a very stoic man who acts mature and sometimes blunt to the point of rudeness when he was with his fellow Devil Hunters, but he is actually fairly softhearted. He has a tendency to get attached to others easily, and hates to see people get hurt, especially his close friends. Unlike many of his associates, he was described by Himeno as being a "normal person", in the sense that he still grieved for those lost and had not become jaded enough to close his feelings off. Despite this, he was very determined and his primary motivation for killing the Gun Devil was revenge for his family. However, he is entirely willing to put his own life on the line to save other people, even if it got in the way of his goals.
He didn't like people who don’t take their job as Devil Hunters seriously or fight for a superficial and materialistic goal like money or, in Denji's case, to be able to touch some boobs, this being one the primary reasons he and Denji didn't get along initially. Aki is also ruthless, stating that he always makes sure the Devils he kills suffer in order to give them a slow and painful death. He could become intimidating with those he still didn't trust enough, like when he threatened Denji by telling him that if he either betrays them or sides with other Devils, he would kill him without any hesitation. Despite being merciless, Aki still has some kindness with his fellow devil hunters, such as retrieving Denji's severed arm, taking Meowy to get medical attention, freeing Power and intentionally lying in his report to Makima in order to uncover the truth of the incident with the Bat Devil.
His air of cold detachment was a façade as he hadl been seen to cry over the deaths of his comrades such as Himeno and he grew to care for Denji and Power enough to try and forfeit his revenge goal in order to keep them safe. Aki also is capable of being afraid to lose those he deeply cares about. Takes things slowly though gets attached quickly.

Swordsmanship: Aki is a proficient swordsman, wielding a sword as his primary weapon when fighting Devils.[5] By using a special sword, made by the Angel Devil, Aki can harm and kill beings that are normally intangible, such as Ghosts. He was skilled enough to defeat multiple zombies and even keep up with physically superior opponents, such as Hybrids, with the help of his Devil contracts.
Hand-to-Hand Combat: As a Devil Hunter, Aki received training in unarmed combat. He displays decent skills in boxing, being capable of easily defeating a boxer far more muscular than him.
Cooking: Aki displays decent skills in cooking, usually being the one responsible for Denji's and Power's meals.
Driving: Aki knows how to drive and had been seen driving vehicles, such as cars.

Aki is a handsome, tall young man with medium-length black hair that he usually wears in a topknot style (shoulder-length with long bangs when untied) and dark blue eyes. In the past when he and Himeno met through Kishibe and became partners, Aki used to have shorter hair.
He often wears the Public Safety Devil Hunter uniform; a suit and tie. He also donned black earrings and usually carries his sword on his back.