Kento Tate, also known by his heritage name Kento Hayato, is a 15-year-old war orphan surviving on conquered Earth in 1995 under Zaar Imperial rule. His father, Hayato Tate (Prince Harlin of Helios), vanished during a sea expedition when Kento was four. During the Zaar invasion, Kento witnessed his mother and sister die, becoming his immediate family's sole survivor. He sustained himself and a group of fellow orphans by stealing food within the ruins of Tokyo.

His life shifted upon finding a hidden base run by Dr. Earl, a refugee from the conquered planet Helios. There, Kento learned he was a descendant of the Helios royal line and was designated the primary pilot for the super robot Atlaus, part of the combining mecha Daltanious. Despite this, Kento consistently rejected his royal heritage, identifying solely as human and expressing disdain for Heliosian customs and politics. He cherished his simple Earth upbringing under his human grandfather, Kazuto Tate.

Shaped by trauma and survival, Kento initially displayed a hot-blooded, cynical, and self-centered personality. He frequently clashed with Dr. Earl over the scientist's elitist view of Earthlings, notably defending his younger companion Ochame when Earl dismissed her as "just some Earthling." Leading Daltanious, Kento piloted Atlaus while his friend Danji Hiiragi operated the fighter Gunper; their contentious but vital partnership, alongside the sentient lion robot Beralios, enabled the mecha's formation.

Significant development followed his reunion with his father, who led a slave rebellion against the Zaar. This intensified Kento's internal conflict over identity and duty. When the Zaar Empire falsely branded him a clone—a stigmatized class—several allies abandoned him, deepening his isolation. After a crushing defeat, Kento suffered a mental breakdown and attempted suicide, though he ultimately chose to fight on.

Kento's resilience stemmed from his bonds with his found family—the orphans and villagers he protected. He remained resolute in prioritizing Earth's liberation over royal ambitions, openly defying nobles who valued titles over integrity. A pivotal moment came when he extended empathy to Kloppen, the Zaar commander revealed as a clone of Prince Harlin. This act spurred Kloppen's defection and helped defeat Emperor Dolmen.

Following the victory, Kento declined a role in the new Galactic Federal Republic led by his father. He returned to Earth with his friends to rebuild the planet, affirming his commitment to his human identity and found family over imperial legacy.