Aki generally appeared to be a very stoic man who 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. Despite this, he was very determined and his primary motivation for killing the Gun Devil was revenge for his family. However, he was entirely willing to put his own life on the line for othes.