Aki Hayakawa (早はや川かわ アキ, Hayakawa Aki?) is the deuteragonist of the Public Safety Saga. He was a Public Safety Devil Hunter working under Makima's special squad[2] who had contracts with the Curse Devil and Future Devil, and a former contract with the Fox Devil.

During the Gun Devil arc, he was killed and possessed by 20% of the Gun Devil, thus becoming the host of the Gun Fiend (銃じゅうの魔ま人じん, Jū no Majin?).

Human Form

Aki was a young man with medium-length black hair that he usually wore in a topknot style (shoulder-length with long bangs when untied) and blue eyes. In the past when he and Himeno met through Kishibe and became partners, Aki used to have shorter hair.

He often wore the Public Safety Devil Hunter uniform; a suit and tie. He also donned black earrings and usually carried his sword on his back.

Fiend Form

After the Gun Devil took over his body, Aki became the Gun Fiend. During this time, his hair was let down and his eyes and forehead were covered in dark veins. The barrel and slide of an M1911 was seen sticking out of his face in between his eyes with the gun’s hammer sticking out the back of his head, Aki's left forearm was replaced with an M4.

Aki generally appeared to be a very stoic man who acted mature and sometimes blunt to the point of rudeness when he was with his fellow Devil Hunters, but he was actually fairly softhearted. He had a tendency to get attached to others easily, and hated 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 was 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 money.