Subaru Hidaka is a second-year student in the same school as Kaito Yashio and Akiho Senomiya who is skilled roboticist that he has won the Robo-One championship several times under the guise of "Mr. Pleiades." Subaru is secretive of his involvement with robots due to promising his father he would undertake the family's fishing business after graduating. Despite initially refusing to join the Robotics Club, Subaru is later blackmailed to join by Kaito.

Tone: Stern, Serious