Masaru Kōmyōji is the younger son of Dr. Nobuhiko Kōmyōji and the younger brother of Mitsuko Kōmyōji. His mother left the family shortly after his birth, and his father, a brilliant but workaholic robotics scientist, was later kidnapped by the evil organization DARK. From a young age, Masaru grew up largely alone, often left in the care of others while his sister Mitsuko searched for their missing father. This upbringing made him emotionally vulnerable and quick to cry, but also forged a resilient and spunky personality. He deeply admires Jiro, the android also known as Kikaider, whom he sees as an older brother figure and a source of strength. Masaru’s primary motivation is to be reunited with his father and to help Jiro and Mitsuko in their struggle against DARK. Despite his age, he exhibits remarkable bravery and resourcefulness. On several occasions, he independently takes action to aid his companions, such as tricking the detective Hanpei Hattori into revealing his sister’s location and then making his way to her on his own. He refuses to be left behind in safe places, insisting on participating in the group’s dangerous quest. Masaru’s relationship with Jiro is especially warm; he treats the android not as a machine but as a true brother, and he is protective of Jiro in return. His bond with his sister is close, though he sometimes feels she underestimates him. Over the course of his journey, Masaru matures from a lonely, tearful child into a gutsy and determined boy who faces terrifying situations with courage. He has no superhuman abilities, but his quick thinking and emotional honesty often prove vital to the group’s morale and success. In the short film Tobidasu Jinzō Ningen Kikaidā, Masaru appears alongside his sister and Hanpei as part of the continuing search for Dr. Kōmyōji, providing a youthful perspective on the ongoing battle between Kikaider and the forces of DARK.