Fifty nationally ranked middle school tennis players receive an invitation to join the Japan U-17 training camp—an exclusive tennis camp that was previously open only to high school players. Amongst the recipients is tennis prodigy Ryouma Echizen and his teammates of the Seishun Academy Boys' Tennis Team. In the camp, the middle schoolers come across many strong opponents as they become intertwined with the camp's hierarchy system. They soon find themselves fighting against the high schoolers—and among themselves—for a spot in the camp as well as the top 20. With the U-17 World Cup around the corner, it is a battle to see who will represent Japan on the world stage.

Shin Tennis no Oujisama depicts the players' resolute endeavors as their tennis skills continue to reach new heights while also learning the meaning of perseverance and resilience. With countries stronger than Japan awaiting them at the U-17 World Cup, the determined tennis players must find a way to work together and ultimately come out on top.