Hirama (平間) is the detective that interrogated Shinichi after Kana's death. He later plays a pivotal role in killing Reiko Tamura.
Hirama is an older man with an average height and build. He has dark grey hair and wears silver rimmed square glasses. His face is quite wrinkled and has thick dark eyebrows. He's always seen wearing some form of suit.
Hirama has a strong sense of justice and tasked himself with putting an end to the Parasites. He had good intuition, knowing even towards the end that Shinichi was hiding something from him. He's also quite compassionate and motivative as he was one of the few detectives to genuinely feel bad for Kuramori and convinced him to help their cause.
Hirama is first seen with his partner Mita. They begin discussing how the parasite that killed Kana was also killed. They believe that the monster may have had a falling out with another of its kind, causing it to be killed after the girl. After Mita notes how calm Shinichi appears, he informs Mita that Shinichi's mother was killed by a parasite. When Shinichi ignores Hirama's hand gesture to speak with him, he notes that he's already interrogated him and pulled some of his hair, and doubts that he killed the parasite.
Hirama is later seen after being requested by Shirou Kuramori. He is quickly informed of the case and sympathizes with him. While Kuramori begins to break down, he reassures him that they will put a stop the parasites and that he can still become a great detective by helping them. He asks Kuramori to write a detailed report about who and what he's been involved in. While in a diner Mita questions why they are being so accommodating to him and Hirama replies that this is the only way they can get a break in the case. After learning of Kuramori's departure, Hirama begins reading the report and sweats from its intensity. Although he questions the lack of any detail about Kuramori's partner, he realizes they need to quickly capture Reiko Tamura.
After reaching her home and picking the lock they discover a note left by Kuramori instructing Reiko to meet him at Hikari Park. The team of detectives and himself quickly head to the location and spread out. Hirama and Katsumata soon find a severely injured and dying Kuramori laying on the ground. Hirama begins asking questions about his partner and where Reiko is. Kuramori replies that she is wearing a white dress and holding a child whose clothes has his blood on it. He tells them that his partner is just a man who lost his small family like himself. While smiling, he states that he'll see his wife and daughter soon. His last words were him saying he's glad that he didn't kill the baby after all. With his death, Hirama promised he'd do everything in his power to not let his death be in vain, and declares him an honorary detective.
He is next seen along with his squad surrounding Reiko Tamura, who is holding her child, and Shinichi. He quickly assesses the situation and determines that Shinichi is indeed human. He begins to question Reiko, who tries to play the victim. Hirama pulls his gun out on her, surprising the other detectives. Promising to be held responsible for any and all outcomes, he shoots Reiko in the head. After a moment of silence, Reiko smiles, compliments his aim, and spits out the bullet. Hirama and the other detectives open fire on Reiko, shooting her all over her body. Reiko uses her parasite ability to protect the baby and walks towards Shinichi. Once she gets close to him, Hirama orders a cease fire to avoid hitting Shinichi and watches in silence. After Reiko passes her child to Shinichi and dies, Hirama calls a cleanup crew. Hirama is seen conversing with his superiors and seemingly being praised. Hirama later berates Mita for trying to arrest Shinichi. Hirama next takes the child into custody for his protection.
A few days later, he along with Katsumata and Mita arrive at a research facility escorting Uragami. Uragami questions as to why he's here again, and wonders what animals he'll be examining today. Hirama tells him that he'll be assessing 5 individuals, Shinichi being one of them. In the isolation room, Hirama and Miyake begin bringing in the subjects. The first is Fukami, a psychic, who Uragami dismisses immediately. He is followed by Nakagawa, though this fails as well as Uragami begins masturbating to the sight of the young woman.
Once they finally reach Shinichi, Hirama asks Shinichi if he can sense anything from the man before him. Uragami jokes about Shinichi's appearance until he takes a closer look and settles down, gaze becoming intent and focused. Hirama begins to take note that Shinichi, for the first time, is nervous and unsettled. Katsumata then asks why Uragami seems like a different person; Hirama replies that this is his true nature. He then asks Uragami, who is deep in thought, if he can feel anything from the boy. Uragami initially claims to see something "inhuman" in his eyes, but then states he was mistaken. Hirama immediately asks him to clarify what he means, but his question is mostly brushed off. From there the procedure ends soon after.
Outside, Hirama promises Shinichi and his father that their home will have police guarding it. Before they leave, Shinichi asks about Reiko's son. Hirama states they'll run tests to make sure he's a normal and healthy baby. If he he's cleared, they'll then put him up for adoption. He says that if Shinichi claims he is Reiko's relative he can adopt the baby, which catches Shinichi by surprise, then states it was a joke. As Hirama watches them leave he wonders what Uragami meant by "inhuman".
Arriving at Director Takizawa's office, he is greeted and introduced to Yamagishi. Yamagishi greets him with his new title and informs Hirama of the possibility of another promotion to Superintendent, causing Hirama to believe he is joking. In the meeting it's decided that Hirama will handle things from the outside, while Yamagishi and his squadrons go on the offensive inside. Hirama then proceeds to suggest using Uragami as an effective way to detect the parasites. Yamagishi rejects the idea, believing a serial killer will be unreliable and hinder their advances. Hirama says that he wouldn't be part of the team, but an extra pair of eyes. Hirama believes that the parasites won't be herded as easily as they suggest. Yamagishi retorts that he's giving them too much credit as being human though, when in reality, this mission will be an extermination.
At City Hall, Hirama sits in one of the buses nearby and watches the soldiers begin to separate out the civilians to detect parasites. After one is killed and no other parasites are discovered, he calls Yamagishi to remind him of the possibility of parasite telepathy as written in Kuramori's report.
At the end of the battle, after Gotou has killed the rest of the soldiers in the building and escaped to confront Shinichi, Hirama pulls out a handgun and shoots him in the center of his chest multiple times. Gotou praises his aim but shrugs it off due to his body armor, choosing to leave instead of dealing with the interference. Hirama then asks what Gotou wanted from Shinichi, which he claims to not know.
Hirama appears again in Shinichi's dream, asking if Shinichi knew anything about Gotou or other information that could have saved the soldiers killed by him.