Tennis prodigy Ryouma Echizen returns from America at his father's request, ready to make a splash in the Japanese tennis scene. Determined to become the country's top player, he enrolls at Seishun Academy, which hosts one of the finest middle school tennis teams in Japan.
After catching the captain's attention, Ryouma earns a chance to compete for a spot in the starting lineup through the intra-school ranking matches, even though he is only a freshman. The rest of the Seishun Boys' Tennis Team are initially reluctant to accept him due to his age, but his skill and resolve eventually win them over.
With their new "super rookie" in tow, Seishun sets out to secure a place in the National Tournament, aiming to claim the championship. To qualify, the team must progress through the Tokyo Prefectural and Kanto Regional tournaments. However, the path ahead is crowded with many strong schools, each with their own unique style of play and motivations. Ryouma and his teammates must learn to work together if they hope to become the champions they dream of being.