"Ryoma! The Prince of Tennis" centers on Ryoma Echizen, a prodigious middle school tennis player who returns to Japan after living in the United States, where he honed his skills under the guidance of his father, a former professional tennis player. Ryoma enrolls in Seishun Academy, a school renowned for its strong tennis program, and quickly establishes himself as a formidable player despite his young age. His arrival disrupts the established hierarchy within the team, as his talent and confidence challenge the older, more experienced players.

The narrative unfolds through Ryoma's journey as he competes in various tournaments and matches, both within his school and against rival teams. The series highlights his growth as a player and his interactions with teammates, who each possess unique playing styles and personalities. Key characters include Kunimitsu Tezuka, the stoic and disciplined team captain; Shuichiro Oishi, the dependable doubles specialist; and Eiji Kikumaru, known for his acrobatic playstyle. The team's dynamics are further enriched by rivals such as Atobe Keigo from Hyotei Academy and Sanada Genichiro from Rikkai Dai, who push Ryoma and his teammates to their limits.

The plot is driven by the team's pursuit of victory in the National Middle School Tennis Tournament, with each match serving as a platform to showcase the players' evolving skills and strategies. Ryoma's matches often emphasize his adaptability and creativity on the court, as he employs unconventional techniques like the Twist Serve and the Drive B. The series balances intense sports action with moments of camaraderie and rivalry, exploring themes of perseverance, teamwork, and the pursuit of excellence.

As the story progresses, Ryoma's past and his relationship with his father, Nanjiro Echizen, are gradually revealed, adding depth to his character. The series also delves into the backgrounds of other players, providing context for their motivations and playing styles. Through its focus on both individual and team growth, "Ryoma! The Prince of Tennis" offers a comprehensive portrayal of competitive tennis, blending athletic competition with character-driven storytelling.