"Buzzer Beater" is set in a distant future where humanity has expanded its reach across the galaxy, encountering various alien civilizations. The narrative centers on the sport of basketball, which has evolved into an intergalactic competition dominated by physically superior alien teams. Earth's team, long considered the weakest in the galaxy, struggles to compete against these advanced opponents. The story begins with the introduction of Hideyoshi, a young and talented street basketball player from Earth. His skills catch the attention of a mysterious benefactor who recruits him to join a newly formed Earth team aimed at challenging the galactic basketball hierarchy.

The team, composed of diverse and skilled players from Earth, is assembled with the goal of competing in the Universal Basketball Tournament. Each member brings unique abilities and backgrounds, contributing to the team's dynamic. Hideyoshi, despite his lack of formal training, proves to be a natural leader and a key player. The team faces numerous challenges, including intense training regimens, internal conflicts, and the overwhelming physical advantages of their alien opponents. As they progress through the tournament, the players must overcome their differences and learn to work together to stand a chance against the dominant alien teams.

The series explores themes of perseverance, teamwork, and the underdog spirit as the Earth team battles against seemingly insurmountable odds. The narrative delves into the personal struggles and growth of each character, highlighting their determination to prove that humanity can compete on an intergalactic stage. The matches are intense and strategic, showcasing the players' ingenuity and adaptability in the face of superior alien technology and physical prowess. Through their journey, the team not only aims to win the tournament but also to restore pride and recognition to Earth in the galactic community.