- Voiced by: Taishi Murata
The protagonist of the story, a compulsively neat high-school honours student who suddenly realizes he has no real goal in life. The manga follows his progress into the world of tennis, as he discovers his passion for the sport and the life-changing effects it has on him.
- Adorkable: He originally cannot speak to Natsu properly and blooms into a blush whenever someone brings her up as a romantic interest. He also gets flustered when people mess with his notebooks.
- Anime Hair: Not as exaggerated as most, but unique enough to identify him with.Aoi (on the phone): By the way, there was a rooster-head kid running around and around the clubhouse.Coach Miura: Rooster? Ahh, that's Maruo-kun.
- Awesomeness by Analysis: Eiichirou's primary method of learning tennis is through careful analysis. When the natural talent Natsu looks at his notebook for the first time, she is amazed to see that he has taken careful notes of everything she's told him and every move he's made, complete with drawn diagrams, angles, and trajectories.
- Badass Bookworm: Goes along with the above. He literally has his nose in a notebook during matches.
- Bunny-Ears Lawyer: Justified. Every new character comments on Eiichiro's strange notebook habit, but his obsessive studying helps him to excel at tennis (and everything else he does).
- Butt-Monkey: At first.
- Class Representative: Is this along with Sasaki.
- Clueless Chick Magnet: Though it's not really emphasized, when you think about it, every notable female character his age is interested in him. Sasaki, Natsu, Aki, even Marcia during the second Florida arc. Eiichirou himself seems clueless about two of these, and would have remained clueless in Aki's case if Natsu hadn't pointed it out.
- Combat Commentator: Eiichiro frequently serves as this in his head during his own matches, as he dissects his opponent's and his own playing on the fly.
- Confusion Fu: As his experience grows, Ei-chan's style is becoming like this. His change-of-pace style, tactical thinking, and the sheer variety of shots he is able to use makes him extremely hard to read, and his data allows him to pick the most effective patterns against his opponents, either catching them off-guard or slowing them down with indecision.
- Crazy-Prepared: What he becomes when he has enough data.
- Determinator: Eiichirou shows shades of this early on, as when he can't remember how he made his first "perfect shot" in tennis by accident, he practices for hours against the wall every day until he can duplicate it. His tenaciousness is also what allows him to progress as far as he does in early tournaments, and many other characters note this as one of his strengths.
- Good Angel, Bad Angel: A variant. During one portion of his training, Ei-chan's Reason and Instinct are often visualized as miniature versions of himself. The point was to make them work together instead of against each other so as to be at his most effective.
- Hidden Depths: Eiichiro is pretty good at singing, if Natsu's shocked reaction to his karaoke is anything to go by.
- Jack-of-All-Stats: Eiichirou himself. He becomes good at all the major shots (lob, serve), court-covering, ball control, etc. However, he lacks any particular finishing shot like other players, which is why it's stated to be his weakness. He grows out of it as the story progresses, gaining an above average serve that he got from mimicking Takuma, and his focus is very much in ball control. He continues to incorporate new moves into his repertoire, creating a change-of-pace playstyle that is incredibly varied.
- Lovable Nerd: Eiichirou, even in universe. Despite the fact that he's pretty nerdy and always at the top of his class, he seems to win the respect and admiration from the majority of his classmates.
- Meaningful Name: Eiichirou's nickname of "All-A" not only refers to the Japanese pronunciation of the first letter of his name, but also to his impeccable grades in every school subject.
- Mega Manning: Eiichirou adopts a variant of the Okada bazooka on the spot against Ogata, as his biggest weakness until then was his lack of power, most glaring against someone with a higher technical degree as Ogata is. Even before this, he is shown picking up small tricks and techniques from many of his opponents.
- Naïve Newcomer: We learn the "Ins and Outs" of tennis through the eyes of novice Eiichirou.
- Neat Freak: Eiichirou values tidiness, which shows in his writing, manner of dress, and how orderly he arranges his boxed lunches. However he truly takes this Up to Eleven with his habit of taking two sets of notes during class, one for studying and lending out to his classmates so that his treasured master copy can remain pristine.
- Nice Guy: Eiichirou. This is one of the reasons that Natsu trusts him with her "big secret" (of wanting to someday become a professional tennis player) on the first day they met.Eiichirou: "Why did you let me in on your secret?"Natsu: "... because it's you. I mean, I know you wouldn't tell anyone."Eiichirou: "But you can't be sure of that!"Natsu:: "I'm sure."
- Super OCD: Eiichiro.
- Took a Level in Badass: The point of the Florida arc. Before that, however, was the tournament where he took a top four place after only getting third-round exits previously.
- Training from Hell: The initial body conditioning training was this, so that Eiichirou could physically catch up to players who have been playing much longer than he has.
- Warrior Therapist: A very rare variety, Eiichiro isn't one intentionally and he doesn't do it using speeches, like the norm. But his Awesome by Analysis strategy and highly adaptive playstyle, while effective for him, also lay out, clearly, what his opponents' weaknesses and shortcomings are. In short, playing against Eiichiro teaches you where you need improvement the most. The best of his opponents have realized this and improved themselves in the middle of the set. Which works out fine for Eiichiro, as he changes to suit the situation and improves himself as well. There's a reason more than one person has thanked Eiichiro for being their opponent, and why some of them ask to see his notes on them.
- Weak, but Skilled: Eiichirou's playing style has no real power behind it, lacking any decisive shots or powerful returns. That being said, he can mentally divide the opponent's court area up into 64 squares and accurately put the ball into any of those squares at will.
- Not so much anymore, he outgrew this after his trip to Florida and his latest match with Takuma, Eiichiro has developed a very decisively offensive control oriented style of tennis, backed by a powerful serve and precise footwork made only possible by complete physical reconditioning to strengthen his muscles and increase his stamina, even Miyagawa who Eiichiro defeated in their last match via a mixture of luck and determination, was quick to notice how he Took a Level in Badass and that he should probably consider him a completely different player. It is of course, difficult to notice the upgrade even for the reader up to that point, since the Manga does a very good job in presenting Eiichiro's progress very gradually, and in a very detailed and borderline realistic fashion.
- Voiced by: Minako Kotobuki
The female lead, in the same grade as Eiichirou and one of the most popular girls at school. Watching her practice tennis is one of the reasons Eiichirou took up the sport, and she continually cheers him on as he develops.
- Beautiful Dreamer: When she is convinced to take a short nap during the date at the pool with Ei-chan. His expression says it all, though subverted in that he's also thinking about tennis.
- Can't Catch Up: Natsu feels like this in regards to Shimizu Aki. It is one of the biggest hurdles she still has to overcome, being otherwise one of the top female players in her age group. She finally beats her for the first time at the All-Japan Junior finals. She also feels like this in regards to Ike Souji. Aside from the obvious gender differences, there's also the fact that they are childhood friends and she started tennis before him. In fact, she introduced him to the sport.
- Character Development: Being with Ei-chan has inspired her to think more deeply and thoroughly about her future and plan out her path, even though planning isn't her forte. By the time of the All-Japan Championships, she's decided to go to university in America on a tennis scholarship in order to give herself better conditions for going pro.
- Cute Clumsy Girl: Initially captivated by her good looks and frank demeanour, Eiichirous first impression of Natsu took a downward turn when she immediately tripped and fell into another students lunch getting food all over the World History notes she had just borrowed from him. Remembering her cute expression when apologizing, however, he realized that he couldnt hold a grudge for long.
- The Ditz: Ei-chan's first opinion of her. It's not without cause because not only does she keep calling him weird about note-taking (while asking to borrow them) but she bumps into someone with food while reading them.
- Innocently Insensitive: Her first meeting with Ei-chan isn't without pain on his end. She calls his note-taking habits weird while he is sitting behind her. She continues to call it (and him) weird to his face. But she's not being malicious about it.
- Oblivious to Love: Zigzagged. On the one hand, not only does Natsu immediately realize what Ei-chan was trying to say to her during his Cannot Spit It Out moment, she also realizes that Aki has a crush on Eiichirou right after seeing how she acts around him. On the other hand, Takuma's feelings for her are obvious to everyone except her.
- Passionate Sports Girl
- Plucky Girl: Eiichirou admires this trait about Natsu. The trope is subverted every time he mentions it to her, as she then immediately tells him of all her inner insecurities.
- Right Behind Me: The first time she's ever heard of him, she calls Ei-chan's habit of taking neat notes 'weird' while he's sitting right behind her.
- School Idol: Kageyama refers to her as "The school's #1 cutie."
- Technician vs. Performer: The performer to Aki's technician, with her mental strength and intuitive style.
- Voiced by: Daisuke Namikawa
The best player at STC at the beginning of the story, he is a year older than Eiichirou and Natsu. With his height and build, he was surely on the road to becoming a pro, but a loss against a genius talent has made that path uncertain. Eiichirou nonetheless looks up to him greatly, and playing with Eiichirou is likewise pulling Takuma out of his slump.
- Brilliant, but Lazy: Takuma starts out this way.
- Can't Catch Up: Takuma to Ike Souji, which presumably is what led to him deciding to not even bother trying anymore, much to the coach's chagrin. He then starts training seriously again when Ei-chan starts showing signs of growth, determined not to let him catch up.
- Delinquents: Has this reputation at school.
- Face of a Thug
- Heroic BSoD: The series begins with Takuma in the midst of one.
- Jerkass: Takuma can often be overly aggressive towards the protagonist, and has a tendency to look down on many characters.
- Put on a Bus / The Bus Came Back: Leaves along with Coach Miura once he graduates and goes pro, just before the Kanto Juniors. He reappears in the lead-up to the All-Japan Championships, winning a tournament in Thailand before heading back to Japan.
- Tall, Dark, and Snarky: Very tall (190 cm / 6'3") and certainly dark-haired, but leans more towards surly and bad-tempered than snarky.
- Took a Level in Badass: Coming into the All-Japan Championships, he is already ranked ninth in Japan and has won three Challenger tournaments after only a year as a pro player.
- Voiced by: Hiro Shimono
Another player at STC, a friendly boy the same age as Eiichirou, whom he quickly takes to calling "Aniki". A decent player, but he is quickly eclipsed by Ei-chan's startling growth.
- Combat Commentator
- Gonk: Yukichi Fukazawa starts off as a normal-looking boy, but his face quickly shifts into an absurdly comic style◊ compared to the rest of the cast.
- Nice Guy: He is always supportive of his friends and his reaction to them becoming better than him is admiration rather than resentment.
- Overshadowed by Awesome: Yukichi is a good tennis player, even making it to the third round of the All-Japan Juniors. It's just that all the other major characters are better.
- The Nicknamer: Calls Ei-chan "Aniki" (much to his chagrin), and refers to Ike Souji as "Shishou".
- Wall of Text: He falls into this when he's giving exposition.
- Voiced by: Taiten Kusunoki
A veteran coach at STC who has trained many professional players. He is the first to notice Eiichirou's talents for tennis, and offers to train him with the aim of going pro.
- Combat Commentator
- The Mentor
- Put on a Bus / The Bus Came Back: Leaves along with Takuma as his coach once the latter goes pro, with Aoi taking on the coaching duties from then on. He and Takuma both reappear in the lead-up to the All-Japan Championships.
Coach Aoi Ryuuhei
- Voiced by: Kosuke Toriumi
A retired professional player and former member of STC, now a coach specialized in physical conditioning. Takes over Eiichirou's training after Coach Miura shifts his focus to Takuma.
- Combat Commentator
- Career-Ending Injury: Coach Aoi's tennis career ended when injuries left him unable to play at the professional level. He chooses to specialize in physical conditioning to prevent others from suffering the same fate.
- Eccentric Mentor: Compared to Coach Miura, he's a lot more laidback and likes to tease Ei-chan, but is still a very good coach.
- The Mentor
- Voiced by: Yuuki
A second grader training at STC. Usually seen taking jabs at Eiichirou while he is a novice player.
- Voiced by: Tomoaki Maeno
Eiichirou's first opponent in an official match, the 5th seed of the Kanagawa Junior Circuit. A serve-and-volley style player.
- Oh, Crap!: Played with. He and his friends have one when the famous players of STC all show up to join Ei-chan, and again when Ei-chan breaks Oobayashi's serve. The impression is broken as soon as Ei-chan serves, though.
- Those Two Guys: With Miyagawa, as they go to the same school.
- Wake-Up Call Boss
- Voiced by: Yoshiyuki Shimozuma
Eiichirou's first opponent during his second year in the Kanagawa Junior Circuit. A classmate from Oosugi High and a member of the school tennis club.
- Unknown Rival: To Eiichirou over their grades.
- Voiced by: Tetsuya Kakihara
A friendly and laidback seeded player a year younger than Eiichirou. A baseliner who focuses on full swing ground strokes.
- Crippling Overspecialization: He has a "rainbow of ground strokes", but also relies only on his ground strokes.
- Heir to the Dojo: His family runs a tennis club.
- Heroic BSoD: Miyagawa had fallen into a slump between losing to Eiichirou at the Kanagawa Junior and meeting him again after the Florida arc.
- Was close to another one in their rematch, when he realized that Eiichirou was actually better than him now, but Oobayashi snaps him out of it.
- Power-Up Food: Kelp tea and pickled plums during a match.
- Those Two Guys: With Oobayashi.
- Voiced by: Shintaro Asanuma
A reserved boy often seen reading before his matches. His parents are artists, and his playstyle is extremely unusual. 3rd seed of the Kanagawa Junior Circuit.
- Brilliant But Indifferent: His accuracy and control could probably have gotten him a lot further if he were actually serious about tennis.
- Confusion Fu: His style is this for his opponents. How do you predict someone who isn't even playing the same game as you?
- Cool Shades
- I Know Madden Kombat: Iwasa Hiromi is quite good at tennis, for someone who uses his skills to "draw pictures" with the ball during a match.
- The Stoic
- Voiced by: Wataru Hatano
One of the strongest players in Kanagawa, and self-appointed rival of Takuma. A baseliner who uses speed and power to overwhelm the opponent.
- Always Second Best: Has never won against Takuma, thus sparking their rivalry.
- Boisterous Bruiser: Araya is one of the strongest players in the series in terms of power, and is also one of the friendliest and most talkative characters in the series. Not to mention loud.
- Character Development: His match with Eiichirou caused him to confront his weaknesses and become a much better-rounded player.
- Lightning Bruiser: Araya's strengths are his power and speed on the court.
- Younger Than They Look: There is usually at least one spectator who wonders if he's really a high school student.
A junior of Araya's in his tennis club. Fights Eiichirou in the first round of the Kanagawa Junior competition leading to the Kanto Junior.
- Advice Backfire: Araya gives Nishimura advice on playing Eiichirou, which mostly consists of "he's a weak, defensive player." The analysis stems from Araya's game against Eiichiro from the prior year, and he has become a completely different player during that time.
- This Cannot Be!: When Eiichirou's tennis game turns out to be much better than advertised.
- Voiced by: Yoshimasa Hosoya
A former member of STC, now based in Florida. Though he is the same age as Eiichirou and Natsu, he has already progressed far ahead and made his debut as a professional.
- The Ace: Ike Souji, considered the best player in all of Japan and respected as the best player in one of the most prestigious Tennis schools in Florida.
- Big Brother Mentor: He gives this vibe with Ei-chan due to how far ahead he is as a tennis player, even though they're the same age.
- Childhood Friends: With Natsu.
- Genki Guy: Very upbeat and cheerful when not playing tennis.
- No Celebrities Were Harmed: As per Word of God, his character was inspired by Kei Nishikori, currently THE best Japanese tennis player, ever.
- Voiced by: Kenyuu Horiuchi
A coach and sports psychologist from Florida Tennis Academy, he first meets Eiichirou on a visit to STC. A very friendly man and enthusiastic about helping young players.
- Heart Is an Awesome Power: As a mental conditioning coach, his teaching relates to improving the player's spirit and mental strength.
- The Mentor
- No Sense of Personal Space
- Voiced by: Hiroshi Kamiya
A pro player training at the academy and Marcia's older brother. An aggressive and powerful player, though that is a common trait at the academy.
- Big Brother Instinct: Has some of this towards Marcia. Especially when she says she'll get a sexier bathing suit for the next time Ei-chan visits.
- Worthy Opponent: Begins to acknowledge Eiichirou as this after seeing him work hard and improve.
- Voiced by: Megumi Han
Marcia is Alex's younger sister and a junior player at Florida Tennis Academy. She is the first to play against Ei-chan when he arrives, but doesn't think much of his lack of ambition. This changes during the second Florida arc, where it's very clear she develops a crush on him.
- Gorgeous Gaijin: In the second Florida arc, her first appearance is in a skimpy bikini. She's first comes into frame shown from the ground up, focusing on her legs and butt, before we see her face. She's an American.
- Younger Than They Look: Eiichirou is shocked to find out that Marcia is only thirteen years old. He was sure they were the same age.
- Voiced by: Takuya Eguchi
One of Eiichirou's roommates in Florida. As a fellow Japanese, he helps Eiichirou find his way around at first. By the time Eiichirou returns to Florida, he has given up on going pro and instead become a coach at the academy.
- Translator Buddy: Acts as this to help Ei-chan communicate with the other English-speaking players.
- Voiced by: Natsuki Hanae
A 16-year old from India, and already one of the top athletes in national competitions.
Ike Souji's coach, who takes an interest in Ei-chan after watching him in practice.
- Awesomeness by Analysis: Notices Ei-chan's strong eyesight after just a single practice session.
- Renowned Selective Mentor: Has produced many top-ranking athletes at the world level, and is said to only be interested in people with very high potential.
A rising tennis star, becoming runner-up at the US Open juniors after only three years playing tennis. Used to play baseball, only starting tennis in high school, and like Eiichirou has very good eyesight. He is Ei-chan's first opponent at the Bradenton Open.
- Gentle Giant: Towers over most of the other characters at 2 meters tall, but a very friendly guy overall and very close to his family.
- Heroic BSoD: Suffered one in his backstory when the pressure and expectations on him as a baseball player finally caused him to blow up and get into a fight. He switched to tennis after that.
- I Know Madden Kombat: Pete is able to apply a lot of his baseball experience to tennis.
- Lightning Bruiser: Has all the power that comes with being big and tall, while also noted to be incredibly speedy.
- Massive Numbered Siblings: While only 4 of them are actual siblings, there are 23 people together in Pete's immediate family.
- No Celebrities Were Harmed: His name and appearance may evoke Pete Sampras.
- "Well Done, Son!" Guy: Towards his entire family; he feels he's betrayed their expectations after they supported his baseball playing for so long and needs to make up for it, even though they don't actually blame him.
- Worthy Opponent
- Voiced by: Takahiro Sakurai
A tennis player from Kanto in the same year as Eiichirou. Has won the All-Japan Junior tournament in the year prior to Ei-chan participating, and is one of the best of his generation. He wins the All-Japan Juniors yet again by defeating Kanda after the latter's win against Ei-chan, and later beats Krishna at the Super Junior finals in Osaka.
- Ace Custom: Even among top players, he pays lots of attention to his racquets and gets them specifically tuned for him.
- Awesomeness by Analysis: Nabae analyzes his opponents and his own style as detailedly, if not more so, as Eiichirou himself; going as far as building an extensive database in his computer. It turns out this is a very effective method of approaching tennis, as he is the first seed of the All-Japan Junior tournament.
- Friendly Rivalry: Being very similar to each other, he gets along fairly well with Ei-chan outside of matches, and has openly shared his analysis of other players on several occasion.
- Shadow Archetype: Nabae Yuu has a similar analytical tennis style to Eiichiro, but has taken it to a level where he is one of the best players in Japan (even better than Takuma).
- The Stoic: Subverted; he is shown to have a quick temper when things don't go his way, but as the #1 seed in Japan, that doesn't happen much.
- Voiced by: KENN
An unorthodox player and 5th seed in the Kanto Junior competition. Not spectacular technique-wise, but known for his mental strength.
- Buffy SpeakIde (thinking to himself): If I hit a 'spah' with a 'tat-tta', then 'gyuun' is a 'tat-tt-ta'...
- Heart Is an Awesome Power: One of his strengths is his ability to synergize with the crowd's excitement to improve his own condition.
- Hero of Another Story: Ide Yoshiaki's back story is completely littered with sports movie clichés. He's given an entire cast of supporting characters, a compulsion to risk forfeiting his qualifying match to help a child in a car accident (and subsequently, a promise to the wheelchair-bound child), an ability to draw strength from his spontaneously huge fan base, and a tendency to always come from behind in all of his games. It's no surprise that his match with Eiichiro spans sixteen chapters and ends in ridiculously dramatic fashion.Random spectator: Wow, it feels like I'm really watching a movie!!
- Homefield Advantage: Ide invokes this by winning over the crowd wherever he goes.
- Keet: Ide Yoshiaki.
- Red Oni, Blue Oni: Often seen with Okada, but the opposite of him in personality.
- Voiced by: Masakazu Morita
From the same club as Nabae, the 4th seed of the Kanto Juniors.
- Combat Pragmatist: Takagi Sakuya uses almost any tactics to win as long as it's within boundaries, including provoking and/or pissing off his opponents.
- Death Glare
- Determinator: The one time Takagi beat Nabae was because he outlasted him in a practice match through sheer endurance.
- Stone Wall: Takagi may use cheap tricks, but even Maruo admits that his stamina is quite amazing. On the flip side, he doesn't have many significant strengths.
- Voiced by: Kentaro Ito
A tall and powerful player, but pessimistic by nature. In Eiichirou's own words, a "super fast offensive type, rising flat shot style baseliner". 3rd seed at the All-Japan Junior.
- Calling Your Attacks: Invoked. He's definitely not the type to do it, but Ide is and calls his attacks for him. He is not appreciative when he finds out.
- Determined Defeatist: Very pessimistic, yet seems to be all the stronger for it.
- Honor Before Reason: Refuses to mix in other types of shots beside his rising flats due to belief in his own style, even though it would be incredibly useful.
- Then subverted when he does try a topspin, and utterly fails. This actually reaffirms his belief in his style and lets him play better than ever.
- Red Oni, Blue Oni: Often seen with Ide, but the opposite of him in personality.
- Signature Move: His rising flat shot. Nearly the only shot he relies on, except for the ultra-powerful jump shot.
A tennis player from Kinsei High, and once a match for Ike Souji until he was injured in middle school. Now recovered and able to play in the All-Japan Juniors.
- Can't Catch Up: Ogata is slowly growing more aware of this, in regards to Ike Souji. Although he could beat Ike when they were younger, his injury had kept him out of the game for a long time. After the initial rush of just being able to play again, his match against Eiichirou and the video of Eiichirou playing against Ike made him realize just how far ahead Ike has already gone. Unlike Takuma, the realization gives Ogata the drive to win that he was lacking up until then.
- Child Prodigy
- Game-Breaking Injury: A hip injury took him out of the game for years.
Formerly in Yanase High, then transferred to Kabai Tech High School. Second only to Nabae in the All-Japan Junior rankings.
- Hormone-Addled Teenager: Gets caught sneaking out of the dorm to date girls, and seems pretty jealous of the fact that Eiichirou and Nacchan are dating, and again when Eiichirou recognizes Marcia in Florida.
- Signature Move: His sinking topspin.
- Spoiled Brat: Until Kabai's training beat it out of him.
- Team Spirit
- The Rival / Worthy Opponent: Acts as this to Eiichirou during the second Florida arc, being also from Japan and very close to Ei-chan in skill level. There is a sense of camaderie between the two, but he's notably not all that friendly about it.
- Training from Hell: Kanda Hisashi's training conditions horrify even Eiichirou, who doesn't know how to stop pushing himself to extremes.
- Voiced by: Yurika Aizawa
A national champion in middle school. She gave Natsu some trouble in their first match, but eventually couldn't hold out and lost.
- Mistaken Identity: In one of the extra chapters, ends up mistaking Yukichi for Ei-chan. Oh well.
- Voiced by: Kaori Ishihara
A top-seeded female player who has trained to become a pro since childhood. Nacchan's fated rival, so to speak.
- Hopeless Suitor: She develops a crush on Eiichirou. Then she finds out he's Natsu's boyfriend.
- Sacrificed Basic Skill for Awesome Training: Her focus on tennis has left her a little...lost on other things.
- Shrinking Violet: Is pretty timid and awkward outside of matches.
- Technician vs. Performer: The technician to Nacchan's performer, with her high technical skill.
Ei-chan's first opponent in the preliminaries. JTA rank 82.
- Happily Married: And expecting a baby, too!
- Salaryman: Works at a bank, while playing tennis in his spare time as an amateur.
Ei-chan's second opponent in the preliminaries, an intercollegiate player from Inada University.
- The Worf Effect: Is seeded sixth for the prelims, but gets utterly dominated by Ei-chan after the latter had time to watch and analyze his data.
A 35-year-old veteran player, the oldest participant at the Championships. He becomes Eiichirou's third and final opponent during the preliminary qualifiers.
- Badass Decay: Was once in the top ten in Japan, but is now at rank 71 due to being past his prime. Still, Coach Aoi states that keeping such a rank at all at his age is pretty incredible, and that he can be a dangerous opponent due to his experience.
- Weak, but Skilled: Has lost some speed and power over the years, but his technique is astounding.
A 28-year-old professional player, eleventh-ranked in Japan and the tenth seed in the Championships. Briefly meets Eiichirou and Natsu at a tennis shop before the tournament.
Ranked fourteenth in the JTA. Serves as Souji's training partner right before the tournament.
The second-ranked tennis player in Japan and second seed of the Championships, behind only Ike Souji.
- Voiced by: Takuma Terashima
Ei-chan's classmate and best friend from Oosugi High. He frequently shows up to cheer for Ei-chan once the latter takes up tennis.
- Dogged Nice Guy: To Sasaki, he goes to work his ass to the ground for her to have a chance to go and cheer Eichiro on the Nationals.
- Shipper on Deck: Kageyama ships Eiichirou and Natsu, though not without his own personal motives.
- Those Two Guys: With Sasaki.
- Voiced by: Asami Seto
Class rep along with Ei-chan himself. Invited along by Kageyama to watch Eiichirou play, she eventually becomes a regular supporter.
- Class Representative: Along with Ei-chan.
- Hopeless Suitor: Also has a crush on Eiichirou, but soon realizes he'd already been drawn into a different world.
- Those Two Guys: With Kageyama.
- Tsundere: Amazingly enough, she becomes this to Kageyama, as she starts to notice the feelings she's developed for him.
Sanae and Kazuya Maruo
- Voiced by: Yuko Kato (Sanae), Mitsuru Miyamoto (Kazuya)
- Education Mama: Eiichirou's mother worries that his deepening involvement in tennis will affect his (near-perfect) grades, leading to his do-or-die "one year" ultimatum.
- Hoist by Her Own Petard: Eiichirou's mother was the one who pushed him into going to the Southern Tennis Club, and start practicing tennis, and not very kindly. A move she probably came to regret months later, when Eiichiro informed her that he wanted to try becoming a professional tennis player, a decision that she very strongly disapproved of.
- Reasonable Authority Figure: In comparison, Ei-chan's father is quite supportive of his goals.
- Voiced by: Takuma Suzuki
A reporter for the Tennis Times magazine. He begins to take notice of Eiichirou as his performance improves.