Haruka is a timid and quiet prisoner. Although he does not speak often, when he does, he stares at the floor. The more you get to know him, the more he starts to speak. As shown in his interaction with Shidou on the MILGRAM Portal Timeline, Haruka has a habit of digging his nails into his palm when he is nervous or tense. He is also not fond of animals, a claim he made in both his interrogation and the Timeline. He also says in his voice drama that he is not good at dealing with children.