Giant Killing is a sports anime and manga series that follows the story of East Tokyo United (ETU), a struggling football team in Japan's top league. The series focuses on the team's efforts to climb back to the top with the help of a new coach, Tatsumi Takeshi, who has a unique approach to tackling stronger opponents. It delves into themes of teamwork, strategy, and the underdog spirit, offering a realistic portrayal of the highs and lows of professional football.