Hirokazu Arai was a Public Safety Devil Hunter in Tokyo Special Division 4, commanded by Makima. He underwent roughly six months of training under his senior colleague Himeno before active duty. Arai stood tall with short, spiky black hair, black pupils, and a distinctive scar on his lower left cheek. He wore a black suit for operations but dressed casually for social events like the newbie welcome party. Arai held strong moral principles, becoming visibly flustered when Himeno offered a kiss as a reward for defeating a devil, insisting young women shouldn't give themselves away before marriage. He viewed himself as fundamentally good, routinely caring for his intoxicated mother after her work shifts and assisting Denji after Denji's distressing kiss encounter with Himeno. Despite this self-perception, he displayed pragmatic survival instincts during the Eternity Devil incident by advocating for sacrificing Denji to secure the team's escape, later actively participating in an attempt to stab him. He harbored envy toward Denji's innate talents as a hybrid devil hunter, considering it a personal weakness. In leisure time, he read and composed haiku. His operational history included assisting Aki Hayakawa in evacuating survivors during the Bat Devil incident. He played a more prominent role during the Eternity Devil mission at the Morino Hotel, initially partnering with Denji before retreating due to fear. When the Eternity Devil offered a contract for Denji's life, Arai supported the exchange as legally permissible, restraining Denji so Kobeni Higashiyama could stab him, resulting in Aki taking the knife wound. After escaping the hotel, he attended the Division 4 welcome party, revealing his age as 22 and his contract with the Fox Devil. This contract allowed him to summon portions of the Fox Devil's body, typically its paws, in exchange for unspecified physical sacrifices. Arai's final mission occurred during the Gun Devil's coordinated assassination campaign against Public Safety Devil Hunters. While walking with Kobeni, an elderly assailant shot him in the neck. In his last moments, he shielded Kobeni with his body, enabling her survival and subsequent intervention to save Denji. This sacrifice resulted in his death. A theory posits Arai's corpse was reanimated as the Violence Fiend, noting physical similarities like comparable height, build, and hair structure. The Violence Fiend's rapid bond with Kobeni and retention of human memories align with Arai's previous partnership. The anime's ending sequence for Episode 11 placed the Violence Fiend between imagery of Kobeni and Himeno, omitting Arai, potentially implying this transformation. This theory lacks explicit narrative confirmation.