Kōtarō Tsukinaka is a third-year student and the captain of the Ryōin Academy rugby club, where he plays as a stand-off. He has been playing rugby for essentially his entire life, giving him a deep well of experience and a profound understanding of the sport. On the field, Tsukinaka is a passionate and determined player who consistently gives his full effort in every match. Despite being smaller in stature compared to many of his teammates and opponents, he compensates with exceptional speed, agility, and quick decision-making, making him a formidable adversary. His rapid movements and sharp thinking often catch opponents off guard. Off the field, he displays a gentle and caring personality, always supporting his teammates and working to lift their spirits when they are down. This blend of fierce competitive drive and genuine warmth makes him a natural and respected leader. A key aspect of his personal life is his close relationship with his brother, who is also a rugby player, and the two share a deep passion for the sport. Throughout the series, Tsukinaka faces numerous challenges both on and off the field, but his love for the game and his determination to become a better player never waver.