Hōō Byōdōin is introduced at the U-17 Camp in Shin Prince of Tennis ranked as the Number 1 ranked Youth Representative of Japan, which marks him as Japan's best U-17 player. He is the leader of the First Returning 1st Stringers, who have just returned from an Overseas Expedition.
They get back to the camp to be welcomed back by the news that middle schoolers have joined the camp and witnessed them defeat a number of the Top 20. He decides to allow the inclusion of middle schoolers on the list of challengers for their places.
Two Years Prior to the storyline, when Byoudouin was only in his 1st Year of High School, he was called up to the U-17 Camp. At this time both he and Oni Juujiro stood out in the camp and the two then faced each other in a fierce and violent match. During the match, Byoudouin demonstrates power that he "obtained from a different dimension." Byoudouin hits incredibly powerful shots, including Pirates of the Americas and Snake Charmer of India, both of which he uses to "split" the ball into 6. Oni manages to return Byoudouin's shots, appearing to turn into a Kishin (Ogre God), and the ball makes direct contact with Byoudouin's head, tearing his bandana and leaving a scar. Oni wins the game set 7-6, and Byoudouin is sent to train at the cliffside for a year.
It is also known that he utterly defeated Kazuya Tokugawa in the previous year.
