Aki generally appeared to be a very stoic person. He 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 cried when his partner Himeno died). Aki became a devil hunter because he saw his family (mother, father, and younger brother) get killed by the gun devil.