Maruo Eiichiro is an honor student in his first year of high school. He's a very methodical person who keeps two sets of notes for class and focuses entirely on his studies. One day, Eiichiro decides to participate in a free trial at South Tennis Club (STC) because he needs some exercise. There, he meets school idol and sweetheart Takasaki Natsu. Eiichiro has taken his first step into the world of tennis

Eiichiro is unable to answer Natsu when she asks him what he enjoys doing most. He becomes interested in tennis and returns to STC for another free trial.

Eiichiro is unable to forget how good it felt when he successfully returned Takuma's serve, and he spends all of his time practicing against the wall. After seeing Eiichiro practice against the wall non-stop for six hours on a Sunday, Natsu predicts that he will quickly improve.

Eiichiro finds himself in a contest with Takuma. Eiichiro has fifty tries to return Takuma's serve. One successful return and Eiichiro wins. However, despite Eiichiro's best attempts to follow his notes and stick to the basics, he can do nothing against one of the strongest serves in the country.

Eiichirō is about to play his first match. He receives advice from the other STC members, but it only makes him more nervous. He doesn't get a chance to calm himself down as he's soon called to the tennis court.

It is down to the final match of the set. Eiichirō trails 5 games to 1, but with a determination to stay on the court as long as possible Eiichirō begins to push Oobayashi.

In order to improve Eiichirō's playing, Coach Miura has him learn control on a 9-square court. After getting the basics done, Eiichirō is forced into a match against Takuma.

Maruo Eiichirō continues his training at STC as he tries to master every shot. At smaller tournaments he begins advancing to the third round but is unable to go further. His mother worries that Eiichirō is spending too much time on tennis when he drops out of cram school to practice more.

Eiichirō returns to the Kanagawa Junior Circuit. His first match is up against fellow high school student Koshimizu Nariyuki, a man whom is always trying to compete with Eiichirō for the top scores.

The match between Eiichirō and Miyagawa begins with each holding serve. However Eiichirō feels that something is off. After studying his notes, Eiichirō realizes that Miyagawa has been studying his shots, and with a 4-3 lead he plans on making his move in the eighth game.

After managing to hold serve Eiichirō starts looking for an opportunity to break Miyagawa. Both hold serve and force a tiebreaker. With the score 6-5 Maruo in the tiebreaker Eiichirō decides to try and gamble to use his full stroke and steal a point.

After defeating Miyagawa, Eiichirō returns to STC for some training that will make him better in 1 day. Eiichirō is teamed up with a Coach Mike from Florida who specializes in pyschological training.

The match between Hiromi and Eiichirō begins. Everytime Eiichirō tries to go on the attack, Hiromi hits a shot Eiichirō can't reach.

It is match 10 of a 1-set match, and Eiichirō leads 5 games to 4. Eiichirō begins to up his speed against Hiromi, and with it he stays even at 30-30. Just then Hiromi's legs cramp up, allowing Eiichirō to get two easy aces and win the match 6-4.

Eiichirō overhears Araya telling Takuma that if he loses to him this tournament, he will retire from tennis. His plan is to defeat Takuma and then announce he is going pro. Takuma agrees to tell Eiichirō Araya's weaknesses.

After going up Love-15, Araya uses a number of service aces to go up 3-1 in set 2. Eiichirō holds serve, and as he gains a 30-40 advantage in Game 6 of Set 2, Araya punches himself in his face to eliminate his emotions from the game.

Araya and Eiichirō end up at deuce after neither player can gain an advantage. An ace end up being huge for Araya give him the match point advantage, and despite his best efforts a lucky bounce proves to be the end for Eiichirō as he loses 6-1, 6-4. The finals are held between Araya and Takuma.

Eiichirō investigates going Pro, but his reaction from his parents is less than he expected. Eiichirō joins Natsu at the first round of the All Japan Pro to watch the debut match of Ike Souji.

Eiichirō manages to steal 1-point in the 10-minute match with Ike before his coaches reappear and make him stop playing a match. Afterwards Eiichirō is sent home to rest. The next day Eiichirō begins a brutal practice regimen that will recondition his body into that of a pro's.

Eiichirō continues his practice and gets his next tournament schedule. As the last player to qualify he is placed up against the 1-seed, Yu Nabae. Eiichirō begins to look for weaknesses from Yu on tape, but what he finds is a highly adaptive style that could easily beat him if he doesn't come up with a few tricks.

Yu Nabae matches up with Eiichirō and realizes they really are two players that are virtually the same. He realizes that what Eiichirō lacks is experience with the fundamentals, as he has never played anyone like himself, and after losing the first set Nabae begins to pull away and goes up 5-2.

In an effort to try and reverse the tide, Eiichirō decides to go back to his idea of having 100-squares to aim for instead of 9.

Eiichirō runs to watch Natsu's match when he learns she is in danger of losing. Afterwards they return to STC where he Ryuhei Aoi, a man who will become his new coach.

Eiichirō and Natsu go out on their first date. When Eiichirō asks Natsu what she thinks about him, she tells him he is cheating. Afterwards Eiichirō is allowed to resume practice.