Ace of the Diamond

Game set. Eijun Sawamura, the pitcher of a novice junior high baseball team, meets with a bitter walk-off loss. For Sawamura, that became his last game in junior high, so he sets a new goal of going to the nationals in high school with his teammates. As he begins his hard quest on studying, a guest arrives unannounced. Her name is Rei Takashima, and she is the assistant director of the prestigious Seidou High School Baseball Team. Takashima invites Sawamura to Seidou after seeing his potential, but Sawamura's reply was far from what she had expected.

Kazuya Miyuki becomes the catcher for Sawamura in a contest against Seido's dangerous clean-up batter, Kiyokuni Azuma. As Eijun tries to pitch down the middle, he finds himself tense and unable to control the ball. Kazuya immediately calls time and comes out to give him some words of encouragement. The words have the desired effect as Eijun finds more control than ever before and unveils a dangerous weapon he didn't know he had. Seeing how people like Kazuya can alter his pitching, Eijun decides to come to Seido as long as he can become the ace of the team.

Eijun is nervous about rooming with older teammates, but they make him feel a too little at home on his first night. Eijun ends up oversleeping and shows up late when it's time to meet Coach Tesshina Katoka, a former Japanese pro pitcher. Miyuki also shows up late, but he uses Sawamura as a decoy to sneak into his line. Katoka shows no mercy and says Eijun can never become a pitcher if he can't show up on time. He also makes Miyuki run laps. Sawamura is determined to prove he can be the ace though, so Coach Katoka gives him a special challenge, saying until he can complete this challenge, he can't play in a baseball game for Seidou.

Seido faces off against Ichidai Third High School, the school that beat them last year. While their top-level offense rakes in runs, the ace Tanba struggles, and the game turns into a batting contest. However Sawamura isn't present. Instead he is training back at school. During his training Furuya, another first-year pitcher, approaches him. Showing sympathy to Sawamura's peculiar training method, Furuya offers to play catch with him. Sawamura is in a cheery mood with Furuya's kindness, but the speed of Furuya's throws far exceeds his expectations.

Coach Katoka, or Shades as Onoda calls him, organizes a game between the first years and the non-starters on the second and third year teams. The goal is to determine who will join the starters for upcoming practice games. When Onoda comes across Katoka in the bath, the coach gives him one final chance to answer his question. After the answer is given, Onoda is allowed into the upcoming game, but when he starts as an outfielder, it could spell doom for any chance he has on the varsity team.

Thanks to the words of fellow first year Haruichi Kominato, Eijun makes it on base. Next Haruichi promises to bring him home and get the first years a run. Haruichi proves to be a brilliant batter, and thanks to his spring Eijun scores. However the first years quickly get three outs, and Coach Katoka says he will call it a game unless all the first years agree to continue. Most want to drop out, but thanks to words of encouragement from Eijun they decide to continue. Eijun is placed on the mound, and Hariuchi is placed at shortstop. The two seem to be wroking effectively together against the older students until Eijun's roommate comes to the plate. Can Eijun find a way to strike out his roommate, who is the #4 hitter for the JV team?

The game concludes, and Furuya and Masuko are promoted to varsity while Eijun and Haruichi are promoted to JV. Along with the promotion comes additional pitchers training for Furuya and Eijun. However their training can only be done with the partners that Coach Katoka assigns them. Furuya is assigned to work with Miyuki while Sawamura is assigned to work with Chris. However instead of catching Eijun's pitch, Chris continually gives him additional work that isn't pitching, making Eijun think the coach has gotten the last laugh and that he won't succeed at Seidou.

Chris continues to leave practice early and give Eijun additional workouts. Eijun believes Chris is slacking off and has given up on making the first string, but what makes him the most mad is when Chris tells him he will never be the ace as long as Furuya is on the team. Rei Takashima reveals she was the one who assigned Eijun to work with Chris because of his knowledge of the game, and when Eijun bad mouths Chris he ticks off Miyuki. Rei ends up taking Eijun to see one of Chris rehab practices and reveals he is the only man Miyuki has never beaten. Eijun realizes Chris was trying to make it where he wouldn't get hurt and begs Chris to teach him baseball.

Sawamura begins to follow Chris every where to try and learn more about baseball. He also sits out of some practices so he can learn how the communication of a team works. Chris finally gives in to Eijun's persistence and catches a few of his pitches. After catching them, Chris informs Eijun he must find his specialty if he is to be truly effective as a pitcher. At first Sawamura is confused. he knows his speed isn't the best and he can't throw breaking balls, so what could be his specialty. Eventually Sawamura decides his specialty is his control, but focusing solely on control lowers his speed and allows him to get slaughtered in weekend a game. Can Sawamura figure out what his specialty truly is before being demoted?

Chris finally tells Eijun what sets him apart is his moving fastball. He reveals all the training he's given Eijun could make him the ace if he does it regularly for one year. However Eijun wants to thank Chris personally by delivering his best pitch to him in a game. One night when he's doing secret practices, Coach Katoka catches him and threatens to split him up from Chris. When Eijun tells him his reason for practicing this way at night, he recommends Eijun start a towel exercise that will improve his flexibility and control. Now with his speed back and his movement becoming better than ever, Sawamura is ready for his final JV game. The only question is will there be a catcher available to help him and catch his moving fastball?