Gaku is a fair medium-skinned man with short black hair that has bangs hanging over his eyebrows, brown eyes and he is always seen wearing a suit. In his later years, his hair is slicked back and has some white streaks. He often wears a bowler hat, brown square-rimmed glasses, and black gloves to obscure his identity. However, beneath this facade laid a deplorable, sadistic amoral psychopath who enjoyed killing. He was very methodical, ensuring two conditions were met: first, that he had someone he could frame and second, there would be a period where the person was alone.