Kenta Sanada is the son of Professor Sanada, creator of the GoShogun robot and discoverer of Beamler energy. Targeted by the Docougar Crime Syndicate after his father's suicide prevents them from acquiring Beamler technology, Kenta finds refuge with the crew of the teleporting fortress Good Thunder. He joins their global fight against Docougar and its leader NeoNeros.

Initially hot-headed and impulsive, Kenta possesses a strong affinity for machines and computers, often distressed by their destruction in battle. His early curiosity sometimes inadvertently endangers the Good Thunder crew, causing friction. Through training, he matures, becoming a copilot and eventually piloting GoShogun when primary pilots are incapacitated, accepting his role in the conflict.

His development includes a deep bond with OVA, his robotic tutor. Programmed by his father for education and discipline, OVA evolves into a maternal figure for Kenta and the crew, offering emotional support and daily care. Kenta also forms a romantic relationship with GoShogun pilot Remy Shimada.

Later revelations expose Kenta's extraterrestrial origin and intrinsic link to Beamler energy. Originating from a Tunguska meteorite impact, this power source embodies Earth's collective soul, encompassing life and sentient machines. Kenta emerges as its positive incarnate, opposing the malevolent NeoNeros. Uniting with former Docougar generals, he defeats NeoNeros in the climax. As the new Beamler embodiment, Kenta pilots GoShogun into space to return to his home planet, transitioning from vulnerable child to cosmic guardian.

In the sequel film "The Time Étranger," set decades later, Kenta is absent as the story focuses on Remy Shimada and the original adult crew during an unrelated crisis.