After training in the United States, Ryoma Echizen returns to Japan to rejoin the Seigaku Middle School tennis team for the 20th National Tournament, determined to lead them to victory. Seigaku advances through the national tournament, confronting rivals and new opponents, climaxing in the championship match against Rikkaidai. After Seigaku's national victory, Ryoma departs once more for training in the United States. He later returns to Japan to participate in the U-17 elite training camp but faces expulsion for violating rules. Despite this setback, Ryoma rejoins the Japanese U-17 team for international competitions, including the U-17 World Cup.