In their fourth-grade days, Hiroshi, Riku, and Dafu established the 'Hikari Club,' a hidden refuge in an old factory. What started as a haven for fun escapades like chess and slingshot target practice takes a dark turn when Hiroyuki intrudes. His obsession with world domination steers the club towards creating a sentient robot, drawing in new members and altering the club's essence. As the project advances, Tamiya questions if he can retrieve his friends amidst Hiroyuki's growing control and the club's lost innocence.