High school student Daichi Manatsu is drawn to Tanegashima Island by a strange rainbow he remembers from his past.
Arriving on the island, he discovers a facility called Earth Engine and is questioned about being a "captain."
Suddenly, robotic beings from Uranus, known as Kill-T-Gang, attack, suggesting a looming conflict.
Daichi's connection to the Earth Engine and his role as a potential captain seem crucial in the fight against this alien threat.
The story hints at a battle for the future of Earth, with Daichi at the center of it, connected to a past shrouded in mystery involving his father.