Deck Afta is a young boy living on the colonized planet Solo. His friends are fellow colonists Cosmo Yuki and Kasha Imhof. After the Buff Clan attacks Solo, Deck flees as a refugee aboard the Solo Ship. He is often shown with Rapappa, a domesticated two-tailed squirrel that rides on his shoulder.

Despite his youth, Deck possesses strong determination and actively seeks to become a pilot for the Ideon, a formidable mecha formed from three combined vehicles. Impressed by his resolve, Cosmo allows Deck to serve as his co-pilot for the Ideon's Ideo-Delta component, also known as Sol Conver. Though displaying initial immaturity, Deck steadily hones his abilities through the conflict, earning recognition as a capable pilot. His responsibilities expand significantly later when Kasha Imhof steps down as primary pilot of the Ideon's Ideo-Buster component, Sol-Amber, enabling Deck to take on a more central role in operating the Ideon.

During the final battle against the Buff Clan, Deck pilots the Ideon against their flagship, the Gando Rowa. He is vaporized instantly when the Ideon is destroyed. Following the cataclysm, Deck's spirit appears alongside Kasha's. They observe a motionless Cosmo before being approached by Kitty Kitten. After Kitty tells Deck to move forward, his spirit departs, implied to be transitioning to a new existence.