Kaito Yashio and Akiho Senomiya go with their teacher, Mitsuhiko Nagafukada, to where the Robo-One tournament is being held, though they have no hotel to check into. As Kaito practises with the robot, he experiences a strange sensation for a brief moment. The tournament soon begins and Kaito manages to use his tactics to get through the preliminaries and into the finals.

Before the final match, Akiho starts to grow concerned about Kaito, who hadn't gotten a lot of sleep prior to the tournament. The final match soon begins against the reigning champion, Mr. Pleiades (Who is eventually found out to be schoolmate "Subaru Hidaka"), whose robot has some fierce tricks up its sleeve. While Kaito's robot is at a disadvantage against Subaru's, Kaito suddenly experiences an inverse of the ailment Akiho has, slowing down time for him, and makes a counterattack, knocking both of them out, though this technically results in Kaito's loss.

Upon returning home, Kaito has a brief encounter with Kill Ballad's creator, Frau Kojiro. As the vice-principal prepares to disband the robotics club, Kaito manages to prove that Mr. Pleiades is in fact their classmate, Subaru Hidaka, meaning the school still technically won the Robo-One tournament, as per the vice-principal's request. With the Robotics Club's disbandment cancelled and Subaru forced to join in order to keep his secret safe from the public, Akiho sets her sights on enlisting help from JAXA to complete their giant robot.