Seishun Gakuen
Katsuo Mizuno & Katou Kachirou are Ryoma's fellow freshmen in Seigaku's Tennis Club. Although, they're not that adept in playing tennis like Ryoma since they both just started playing tennis; they just make it up by majorly supporting other team regular members and mostly supporting Ryoma, who, for them, represents the whole of the freshmen tennis members.
Horio Satoshi is a freshman like Kachiro, Katsuo and Ryoma. The only thing that separates Horio from the other freshmen (aside from having 2 years experience in Tennis) is his mouth. He's always shooting off with his mouth. He loves to boast almost anything to his other fellow freshmen even if the subject of his boasting is not himself. He's just full of nonsensical information. Although he loves to boast, he's really loyal to his Seigaku Tennis Club family.
Ryuuzaki Sakuno & Osakada Tomoka are also freshmen and Seigaku's self-made cheering section (although they mostly cheer for Ryoma). Sakuno (the girl in pig-tails) is the team coach's grand daughter. While Tomoka is her bestfriend. Both have huge crushes on Ryoma although Tomoka is the more verbal of the two about it.
Sophomores are the ones who caused problems to Ryoma from the start. Also the main person who started it all is Masashi Arai, a second year wanna-be regular. Although after some time, they stopped buggering Ryoma and just supported him much like what they do to the other regular players.
Coach Sumire Ryuuzaki is the coach of Seigaku Tennis Club for over 10 years. She's Sakuno's grand mother and very scary when it comes to practice. She's very strict and stern about her players. She's also been the coach of Ryoma's father when he's still in Seigaku. She's a decent player when she's young and had been able to teach Nanjirou decent tennis plays like how to overcome Nanjirou's terrible back-hand shots. Which lead Nanjirou to his Nitouryuu technique.
Tezuka Kunimitsu is Seigaku Tennis Club's team captain. He uses nitouryuu like Ryoma and Nanjirou although he's more like Nanjirou in a sense. His dominant hand is the left hand. He's very stoic and quiet during practice although you may hear him ordering for the usual 10 laps to 20 laps around the courts as a sign of punishment for the team members especially if they're being unruly. He is very skilled in playing tennis, so much skilled that he's known nationally (and even internationally). He has the reputation of being undefeated although for how long.. we will see. He's got plenty of tennis techniques although the most popular are his Zero-Shiki Drop Shot and Tezuka Zone.
Fuji Syuusuke is a third year like Tezuka. He's the Tennis Prodigy more like Ryoma. He's the only one who survived Inui's doomed experimental juices. He's always shown in the anime smiling and he's rarely serious when playing tennis, but when he's serious, you can count on the appearance of his special moves: the Triple Counter, which consists of Higuma Otoshi, Tsubame Gaeshi and the ever elusive Hakugei. He could also use Cut Serve or the Disappearing Serve.
Oishi Shuuichiro is the Vice-Captain of the tennis club. He's also the Mother of the entire tennis team since he's worry-wart and very concerned about the welfare of every member. He's the most responsible of the team (aside from Tezuka). He's also the other half of the famous Golden Pair or Seigaku Tennis Club (the other is Eiji). His most famous technique is the pin-point and precise Moon Volley and he could also do Spin Serve.
Kikumaru Eiji is the acrobatic player of the team. The self-proclaimed neko-person (cat-person) of the team because of his antics, mannerisms and voice. He's the other half of the Golden Pair. He's very playful and the only person that keeps him in line is his *cough* partner *cough* Oishi. His play style is acrobatic which makes him able to hit the balls that are usually not within his reach.
Inui Sadaharu is the most intelligent of the team. Technically. His play-style is Data Tennis, tennis data is his specialty, computing angles and speed of balls are his forte. He's always have a notebook in his hand ready for new information being divulged. His past time is making juice which has terrible tastes and make the losers of practice matches drink it. That's why he's being feared by his team-mates.
Kawamura Takashi have a split personality. If he doesn't carry a racket, he's the timid and quiet type but when he holds a racket, he becomes aggressive and always shouting. His play style relies on his strength. His family owns a sushi restaurant and he would become a chef after highschool to continue their family business. His special move are his strong Hadoukyuu, Dash Hadoukyuu and Burning Serve. The idea of hadoukyuu originally came from a player of Fudoumine high.
Kaidoh Kaoru is a second year in Seigaku. He's called Mamushi (Viper) by Momoshiro. He is easily angered and very fearsome when angry although he has a soft spot for cats such as Ryoma's cat, Karupin. He and Momoshiro are bitter rivals/enemies since they both joined the club. You will know he's coming because of his trademark sound "Fushuuu" much like a snake. His special moves are Snake Shot, Boomerang Snake and Hadoukyuu Boomerang .
Momoshiro Takeshi is the friendliest of the bunch almost as friendly as Eiji. He's a second year and bitter rival of Kaidoh in every single thing. His tennis style relies on his strength much like Kawamura. He is the closest to Ryoma since they're always walking together to and from the school. His special moves are Dunk Smash, Super Great Momoshiro Special and Jack Knife.