Seishiro Nagi's relationship with soccer evolves significantly throughout the story. At first, he is shown to be a talented but selfish player who only cares about winning at all costs. However, as the story progresses, Seishiro learns the value of teamwork, sportsmanship, and perseverance. He starts to prioritize the well-being of his team and values the friendships he forms through soccer. Ultimately, Seishiro undergoes a transformation where soccer becomes more than just a game to him - it becomes a source of personal growth and fulfillment.