Kyo Sogoru is a high school student living in the coastal city of Maihama, where he leads a seemingly ordinary life filled with school, friendships, and his greatest passion: swimming. A devoted member of the school swim club, he is determined to keep the club active and often spends time in the pool. His routine is upended when he notices a girl named Shizuno Misaki at the pool and realizes that he is the only person who can see her. This encounter pulls him into a hidden conflict, as Shizuno asks him to pilot a giant robot for an organization called Cerebrum in exchange for her help with a swim club promotional video. Agreeing to her terms, Kyo soon finds himself fighting alien entities known as Gards-orm inside a game-like digital battlefield, all while grappling with a growing sense that the world around him is not what it seems. He eventually discovers that the Maihama he knows is an artificial simulation, a server-based illusion designed to preserve human consciousness, and that his own existence is tied to this digital construct. This revelation forces him to confront profound questions about reality, identity, and memory.

Kyo is an enthusiastic and energetic teenager who earns good grades and approaches life with a genuine love for swimming. His outgoing nature is paired with a reckless streak and a tendency to become easily frustrated when circumstances defy his understanding. Despite these impulsive moments, he shows deep loyalty to his friends and a fierce determination to protect the people who matter to him, whether they exist in the simulated world or the real one. His central motivation is to safeguard both the illusory Maihama and the real world, driven by a belief that the bonds and emotions experienced within the simulation hold genuine value. As the protagonist, he serves as the Gunner of the Altair Zegapain, a specialized mecha unit that requires a pilot and a wizard operator to function. He proves to be a talented pilot, capable of adapting to the demands of combat against the Gards-orm.

His most important relationships shape much of his journey. Shizuno Misaki is the catalyst who introduces him to the truth and remains a steady, if enigmatic, presence. Ryoko Kaminagi, a close friend and filmmaking partner, transitions from his everyday life into the real-world crew of the Oceanus, eventually becoming his wizard inside the Zegapain, forming a vital partnership. Through interactions with other Cerebrants such as Chris and Arque Avenir, Kyo learns about the fragility of memory and the lasting pain of emotional wounds. Over the course of the story, Kyo’s development is marked by his movement from confusion and denial to acceptance of reality’s harsh nature. He wrestles with the knowledge that his own memories may be incomplete and that the world he cherished is a reconstruction, yet he channels that pain into a resolve to continue fighting for the sake of those he loves. His notable abilities center on his proficiency as a mecha gunner and his capacity to operate the Altair Zegapain with skill and instinct, making him a critical asset in the struggle to protect humanity across both simulated and actual worlds.