Aki generally appeared to be a very stoic person. He acted mature and sometimes blunt to the point of rudeness when he was with 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. He didn't like people who do not take their job as Devil Hunters seriously or fight for a superficial goal. Aki was also ruthless, stating that he always makes sure the devils he kills suffer.