Kyousuke Tsurugi is a main protagonist of Inazuma Eleven GO Chrono Stone. He initially appears as a cold and distant forward who claims to despise soccer, a stance rooted in a childhood trauma. His older brother, Yuuichi Tsurugi, suffered a severe leg injury while trying to save Kyousuke from a fall, an accident that left Yuuichi unable to walk. Blaming soccer for the accident, Kyousuke grew resentful of the sport and accepted a role as a SEED agent for the controlling Fifth Sector, tasked with infiltrating Raimon Junior High and ensuring the team follows the organization's predetermined outcomes. Despite his external hostility, Kyousuke is a naturally gifted player with exceptional kicking power and technique, known for his ferocious style on the field. His signature moves include the Death Sword and other powerful shooting techniques that can break through even the strongest defenses.

As the story progresses, Kyousuke's encounter with Tenma Matsukaze and the rest of Raimon gradually changes his perspective. Tenma's unwavering passion for soccer and his refusal to give up on teammates slowly breaks through Kyousuke's emotional walls. This relationship becomes central to his development, as he learns to trust others and rediscovers the joy of playing freely rather than under orders. Kyousuke eventually becomes a loyal member of Raimon, later playing for Entaku no Kishi, captaining El Dorado Team 01, and joining Chrono Storm in the fight against the time-manipulating antagonists. His relationships with his brother Yuuichi, whom he wants to see walk again, and with Tenma, who rekindles his love for the game, drive his transformation from an antagonist into a determined and selfless teammate. He matures from a brooding loner into a reliable forward who channels his strong emotions into powerful plays, ultimately helping to protect the future of soccer itself.