Joon-il, who was once a national team-level prospect, now just a coach at a local soccer class. He is on the verge of being fired for his old-fashioned mind and lazy coaching, and is about to get divorced. Joon-il is given a mission he can't refuse in exchange for a full-time job. It was the final round of the amateur futsal tournament of the "Cheolsoo Soccer Team." In a very short period of time, Joon-il had to transform President Kim, Mr. Choi, and Mr. Park who had no previous knowledge of the sport... Oh my futsal! With the dreams and livelihoods of grown-ups on the stake, "Sunday League" begins!