Kō Kitamura, son of the owner of Kitamura Sports, lives in the same neighborhood as the batting center run by the Tsukishima family. Due to their proximity and the relationship between their businesses, the Kitamura and Tsukishima families have been close for many years, with their children going back and forth between the two homes like extended family. Because Kō and Wakaba are the same age and always together, Aoba is jealous of all the time Kō spends with her older sister. Aoba is a natural pitcher with excellent form, and Kō secretly trains to become as good as she is, even while publicly showing little interest in baseball. Then Wakaba dies in a swimming accident at a summer camp during fifth grade.
Before the scrimmage Daimon tells Azuma that Shido will not fire him even if the varsity team loses, and Shido confirms this. However, during the first inning, Tubby's grandfather, who is the school's chairman, tells Shido and Daimon he is ratifying the wager with Maeno. During the first two innings, Ko allows the bases to get loaded before striking out the next three batters, and to focus him, Akaishi tells Ko to pitch as if it were late in the game. In the sixth inning, the game still scoreless, Daimon asks Azuma who were the portable team's opponents in their practice matches; Azuma says they played top teams from the prefectural tournament, and that Ko pitched easily the first six innings to give his team fielding practice. In the seventh inning, Aoba hits a single and then scores on Senda's sacrifice fly. During the final innings, Azuma asks Daimon if he wishes he had better hitters in his lineup, such as Miki, and as Ko strikes out the final three batters, Azuma says Ko is now the best pitcher they have played against all year. As the portable team celebrates their win, Aoba silently tells Wakaba that Ko did it.
In the bottom of the 12th with Seishu leading 2 to 1, because Ko is tiring, Akaishi tells him to pitch all out to decide the game now. With two outs and a runner on first, Mishima comes to bat. Still pitching in the high 150s km/h, after reaching a full count, Ko walks Mishima with what Junpei calls the fastest pitch of the day. As Aoba watches Ko strike out the last batter, she remembers what he said before the game: that Seishu would go to Koshien, he would pitch 160 km/h, and he loves her more than anyone. After the game Ko hugs Aoba, who slaps him, saying she hates him more than anyone, then cries into his chest. The morning before traveling to Koshien, Akaishi visits Akane in the hospital, Nakanishi consoles Azuma for losing Aoba, and Aoba and Ko meet at a cafe near the train station, where they talk about Wakaba and Akane's influence, and then leave holding hands. During the closing credits, a newspaper headline says that Ko's final pitches reached 160 km/h.
Fifth-grader Ko Kitamura was born on the same day in the same hospital as his neighbor, Wakaba Tsukishima, who treats him as her boyfriend as a result. One day during summer vacation, she makes him take her to swimming lessons on his bicycle. On the way back, to avoid classmate Osamu Akaishi, who has a crush on Wakaba, Ko joins a sandlot baseball game organized by another classmate, Daiki Nakanishi. Because he has never played before, Ko fields badly, but because he has practiced in the Tsukishima family's batting cages he hits the game-winning home run. After their joint 11th birthday, Wakaba gives Ko a schedule of birthday presents for him to give her through age 20. Soon after this, Wakaba drowns while saving a younger girl at an overnight swimming camp. Ko does not know how to respond to this until, the evening after her funeral, he sees Akaishi weeping outside Wakaba's house and realizes he just needs to cry. The closing credits show time passing and by the end, Ko and Wakaba's younger sister Aoba Tsukishima are in junior high school.
In the seventh inning, Ko strikes out Mishima with pitches reaching the high 150s km/h, though Ko is disappointed he did not show Aoba a 160 km/h fastball as he promised before the game. In the eighth inning, Oikawa tries to repeat the previous year's line drive to Ko, but Ko catches it. In the bottom of the ninth, Ryuo manages to score, sending the game into extra innings, tied 1 to 1. In the top of the 10th, Azuma hits a triple, after which Oikawa intentionally walks Akaishi and Ko, to load the bases with no outs. However, Seishu's last three batters are unable to hit, stranding the runners on base. As Seishu takes the field, Azuma warns Ko to not let Mishima get on base or Ryuo will keep the momentum. With Ko still pitching in the high 150 km/h, Mishima hits a hard line drive to first that Azuma barely catches. Aoba remembers seeing Ko cry while practicing pitching shortly after Wakaba died. In the top of the 12th with two outs, when Ko comes to bat he remembers hitting home runs in the Tsukishima batting cages, and as he does so hits a home run.Watch Now:Amazon
Aoba arrives at the stadium in time to see Ko's first pitch at the bottom of the first inning. On the mound, Ko tells Akaishi about Akane's surgery, and Akaishi is annoyed at being kept in the dark. Ko consistently pitches over 150 km/h and retires all three batters with two strikeouts. Before batting in the second inning, Azuma tells Akaishi his only regret staying with Seishu is never getting to face Ko's pitches. Ryuo's pitcher Oikawa walks Azuma but strikes out the rest of the side. In the bottom of the second, Mishima gets on base with a drag bunt, and while on first base tells Azuma he did it to keep Ko from having a no-hitter. No other batters get on base in the first six innings except by walks. In the seventh inning, Azuma hits a single, then is batted in by Akaishi, a hit that Akane watches from her hospital room. Seishu leads 1 to 0.Watch Now:Amazon
After the scrimmage, Shido and Daimon are fired and most of Daimon's varsity players follow him to another school. Yuhei Azuma stays and begins living with the Kitamuras because the baseball dorm is closed down. Because Ko's stamina flags during the fall prefectural tournament, Azuma makes Ko begin jogging to school instead of taking the train. A boy asks Ko for an introduction to Aoba, and Ko congratulates him as the 100th person to do so. When Azuma asks Ko about a photograph of Wakaba, Ko admits that he was in love with her, and Azuma responds that "you guys" have it tough. To get the five most persistent boys to stop asking her out, Aoba goes on a date with all five at once. When Junpei asks about his pitching form, Ko is surprised but says that he based it on Aoba's. Aoba explains to Ko that Junpei's promising career as a pitcher was ended by an injury before he could go to Koshien, and that Yuhei is trying to reach Koshien in his place. Ko tells Aoba he is also serious about going to Koshien, to make Wakaba's last dream come true.Watch Now:Amazon
Ko promises Akane he will tell Akaishi that she will be out in a couple days, saying that he is a pretty good liar. Akane tells him that her surgery will be on the day of the tournament final against heavily favored Ryuo, so she will have to put off their date, then asks him to tell Aoba the truth. Ko tells Akaishi the lie, then asks Aoba to visit Wakaba's grave with him. While there, he prays that the surgery is successful and tells Aoba that Wakaba would not let her cry again. At practice, when Aoba jokingly asks Azuma out to a movie, he asks if she means to ask him out so lightly, saying he seriously likes her. The morning before the game, Aoba asks Ko if he likes Akane more than herself, to which he asks if he can lie. While warming up in the stadium, Ko spots Momiji, who flashes him a peace sign, after which he celebrates. At the hospital, when Akane's surgery is over, Aoba tells Momiji by text message to give Ko a peace sign to tell him it was successful.Watch Now:Amazon
Knowing they will not be promoted, Maeno's third-year players stop playing hard, but after the portable team manager, Hiroko "Tubby" Ōkubo, tells Makihara that Daimon injured Maeno's head as the latter pleaded to give a third-year player a spot, Makihara plays with renewed effort. At the end of eight innings, Ko notices that if the score remains 5 to 3, he will win his bet with Aoba. In the top of the ninth, the portable team gets runners on first and second and Makihara advances them with a sacrifice bunt. Ko hits both runners in with a single to tie the game. While Ko is on base, Azuma criticizes his pitching, to which Ko says he did not expect Azuma could hit him. In the bottom of the ninth with a runner on first, Azuma comes to bat and deliberately fouls out twice before being struck out by Ko. On the bench, Azuma silently tells Ko to stop smirking, and the next batter hits in the runner to win the game. Afterward, Ko visits Wakaba's grave to tell her about his debut, only to find Aoba had been there first.
The girl, Akane Takigawa, apologizes to Ko for the construction noise. Later, Ko tells Azuma he does not know whether Akane really looks like Wakaba would now, because in his mind Wakaba is still in fifth grade. Mizuki invites Aoba to a summer festival the next day. Ko dreams of going to the festival with Wakaba, as she promised before she died, then of running to meet Akane at the Takigawa's soba restaurant. The next day, the anniversary of Wakaba's death, Aoba tells Ko to report his tournament result to Wakaba when he visits her grave. On his way back, he meets Akane wearing a yukata similar to Wakaba's. On her way to Wakaba's grave, Aoba sees them walking together and asks Mizuki if ghosts grow up. At the festival, Akaishi also sees them and asks Nakanishi the same quesiton. Ko and Akane meet her parents at the festival, and after parting with them, Ko meets Momiji, Ichiyo, Aoba, and Mizuki. When Aoba asks where his companion went, they begin to squabble but suddenly stop when the Tsukishimas see Akane at random through the festival crowd.
Four years later, in the fall of her second year at Seishu Junior High School, Aoba is a pitcher for the baseball team, and still hates Ko for having monopolized her dead sister's time. Starting pitcher Keiichiro Senda, who considers himself popular, asks her out on a date without waiting for a response. When she does not show up, Senda goes to her house but is frightened off by the family cat. When Ko (in his third year at Seishu Junior High) delivers baseballs to the Tsukishima batting cages, he hits four home runs, which annoys Aoba, especially since she cannot match it. In a flashback, she remembers Wakaba telling her about Ko's potential to one day pitch 160 km/h fastballs, which Aoba claimed was her ideal in a man, but that if he does, Aoba cannot take him from her. Meanwhile, inspired by Aoba's pitching, Ko has been obeying Wakaba's order to follow Aoba's workout routine.Watch Now:Amazon
Nakanishi recruits Ko for a rematch of the sandlot game from fifth grade. When Ko warms up with what he calls a few soft pitches, Nakanishi has him play right fielder instead, claiming he wants a friendly game. Meanwhile, when Aoba plays catch with her little sister, Momiji, she is startled to learn that Momiji can handle her hardest throws because Momiji has helped Ko practice. Akaishi, now captain of the junior high school baseball team, watches the sandlot game and is reminded of Wakaba's boasts about Ko's abilities. With Ko's fielding and batting, his team wins in a close game. Afterward Nakanishi learns that Ko did not join the baseball team, despite his surprisingly fast fastball, because Nakanishi had been kicked off it for fighting. During practice, Aoba and Akaishi discuss unsettling rumors about the Seishu High School baseball team, which has had a second straight losing year. In his office at Seishu High School, Acting Principal Shido tells a man dressed as a coach that he is pleased with his plans.Watch Now:Amazon
Because of their fall record, Seishu is not invited to the spring Koshien tournament. Akane wins that year's Koshien poster art contest with a painting of a pitcher that Aoba claims depicts Ko's form. Ko corrects her, saying that Akane based it on his photos of Aoba, which he had used to model his pitching style. From Akaishi, Akane learns of Wakaba's relationship with Ko. Aoba tells Azuma she will try out for the women's national team in March, and when she teases him about being given chocolates for Valentine's Day, he says the only girl he would consider going out with is her. For Valentine's Day, both Aoba and Azuma receive many chocolates. When Aoba drops Ko's chocolates off a bridge, she buys replacements, including one extra to give to Azuma for her. When Ko delivers it, Azuma says that he likes Aoba because she is hard to figure out, because she is not true to herself. That evening, Akane asks Ko to show her photographs of Wakaba. As she looks through his albums, she comments that it is obvious Wakaba loved him, and would still love him today. As she leaves, she gives him chocolate.
As the scrimmage starts, Daimon tells Shido he is using Senda as starting pitcher to test his team's fielding. In the top of the first inning, the portable team is quickly retired. In the bottom of the inning, Ko quickly pitches out the first three batters, which Daimon attributes to luck but Azuma recognizes is based on Aoba's batting data and Ko's ability. After Senda gives up three runs in the top of the second inning, including home runs by Ko and Akaishi, Daimon kicks him off the varsity team and Maeno substitutes him in as shortstop for the portable team. Ko pitches fastballs down the middle to Azuma, which Aoba calls foolish and Azuma hits for a home run. The portable team quickly retires the rest of the side but has trouble hitting against the best varsity pitcher. After Daimon chews out his players for failing to hit against "small fry," they manage only one run in the third inning. At the end of three innings with the portable team ahead 3 to 2, Ko complains of being tired.Watch Now:Amazon
Akaishi and Aoba visit Akane in the hospital, where she tells them that she promised to go on a date with Ko after the tournament, and that she may require surgery. In the semifinal, Seishu plays Nishikura, a team that has come from behind to win every game by one run. Senda hits a home run on first pitch of the game, and Nishikura scores a run in the first inning as well. Spurred by Akane's worries, Akaishi hits another home run in the second inning. In the eighth inning, with Nishikura having failed to get on base since the second inning, Seishu scores six runs. Nishikura does not score in the bottom of the inning and the game is called for Seishu, 8 to 1. After the game, Ko finally visits Akane in the hospital for the first time, where he praises Akaishi's performance and then asks when her surgery is.
When Akaishi meets Momiji, he is startled by her resemblance to Wakaba, who died at the age Momiji is now. Ichiyo reminds Aoba that she resented how Ko monopolized Wakaba's time, and both Ichiyo and Akaishi tell Aoba that she and Ko are alike in their competitiveness. In the park, Momiji plays catch with an old man who is a regular at Akaishi's family's liquor store. Daimon tells Shido that an upcoming scrimmage between varsity and portable teams will demonstrate how much better the varsity players are. Because of a rumor that portable players who perform well might be promoted to varsity, the third-year players train hard. Before the scrimmage, Ko has Aoba catch his pitches because he has never played in a real game and so has no comparison for his pitching. She calls them okay, which pleases him as the best compliment he can expect from her, and makes a bet that he will hold the varsity team to ten runs, which she changes to five runs after looking at her bruised hand. When Aoba arrives at the scrimmage, Momiji's old man tells her Shido has ordered the audience to sit and cheer only on the varsity side of the field.
Ko enters Seishu High School and joins the baseball club along with Akaishi and Nakanishi, where they are put on the second-string "portable" team headed by former Head Coach Maeno. Most of the varsity team are ringers recruited by new Head Coach Daimon from around the country, including power hitter Yuhei Azuma, the boy from the batting center, and Daimon promises Shido that he will take the school to the national spotlight of Koshien within three years. When Aoba, now captain of the junior high school team, visits a high school team practice, she is surprised to see Ko playing baseball, and he tells her he was inspired by her pitching. In class, Azuma does not recognize Senda (who is on the varsity team) but does remember Ko from the batting center. Azuma tells Daimon that he only remembers faces of significant people, of which there are four on the team. One day as the portable team practices on the junior high field, out of sight from the varsity players, Maeno has Ko pitch at full strength once and Aoba realizes Ko is Akaishi's "secret weapon" for getting off the portable team.Watch Now:Amazon
The day of Aoba's tryout for the women's national team, Ko and Azuma see her off at the train station. During the journey, Midori, Matsuyama, and Kojima tell her that her play during Satomi's match with Oka a year ago inspired Satomi to win the girl's high school championship. At the tryouts, the Satomi players point out Shimano from Ryuo, who looks and plays like her cousin from the boy's team. In Tokyo, Ko waits out the rainy day in Akane's soba shop. During her batting tryout, Shimano is overshadowed by Oka's Ozaki. Kojima and Oka's Sawaguchi watch Aoba's pitching and are impressed by how her speed and control have improved. Before the coaches announce the results, Shimano insists on showing how she bats against a pitcher instead of a machine, and draws Aoba as her pitcher. Aoba strikes her out with three pitches, and Aoba, Matsuyama, and Midori all pass the first round of tryouts. At Seishu's practice the next day, Aoba pitches to Azuma, a challenge they both enjoy, until he hits her with a line drive.Watch Now:Amazon
Akaishi tells Ko and Nakanishi about Daimon's career as a coach who cares more about results than his players, and suggests they drive him out. Daimon tells Azuma that he picked Senda for the varsity team to be a pitcher who can be used up during practice, then recruits Aoba as another disposable practice pitcher. When Ko, Akaishi, and Nakanishi watch her pitch, Daimon tells them it does not matter if she pitches too much because, as a girl, she cannot play in a tournament game. When Azuma takes his turn at bat, he asks her to not hold back, and in response she insists that Akaishi be her catcher. Pitching her fastest, she almost strikes out Azuma. After Akaishi accuses Azuma of not being manly for deliberately fouling back, Azuma hits a home run on the next pitch and Aoba collapses exhausted. Afterward, Aoba tells Ko that despite her sore arm she will continue pitching for the varsity team to learn their batting weaknesses, and that she wants to believe Wakaba's claims about him.
After giving up a fourth run in the second inning, the Satomi pitcher, Kojima, asks to switch positions with Aoba. The Oka players are startled by Aoba's 130 km/h fastball, at the upper range for female pitchers, and she strikes out their best batter, Ozaki, all of which annoys Oka's pitcher, Sawaguchi. In the fourth inning, Aoba bats in two runners with a double. After Ozaki figures out Matsuyama's call patterns and Oka scores a fifth run, Aoba asks to give the signals instead. In the sixth inning, Aoba scores when the irritated Sawaguchi makes an error, and then Satomi scores a second run. In the last inning, with two outs and runners on first and second, Aoba bats but is caught out by Ozaki. Oka wins 5 to 4. After the game, the Oka coach asks Aoba to try out for the women's national team in the spring, and the Satomi team captain thanks her for pitching. When Aoba returns to practice with Seishu, she repeatedly strikes out the players who wanted to avoid hitting her, and Akaishi says they still need her.
When Seishu wins another game in the tournament, Mizuki complains because it means putting off camping with Aoba. Because she is not feeling well, Akane does not go to work nor to the game, which worries Akaishi. Based on Aoba's coaching, Ko adjusts his pitching form during the next game, which sacrifices control but gives him a speed near 160 km/h. Despite his walking many batters, Seishu wins to advance to the quarterfinals. Ko tries to explain to reporters how Aoba is important to himself and the team, even though she cannot play in tournament games. Akane enters the hospital to be tested for an unspecified illness, which disturbs Akaishi's focus. When Aoba visits her, she is startled by Akane repeating something Wakaba once said about Ko. During the quarterfinal game, Akaishi is still distracted, but with Ko's improved control while still maintaining his speed, plus Azuma's batting, Seishu wins.
On New Year's Eve, Aoba's father and oldest sister, Ichiyo, visit her sick grandmother, leaving Aoba to care for Momiji, who is down with a cold. When Ko visits, he brings the ingredients for rice porridge. When Momiji's fever spikes, Ko helps Aoba tend her until the fever breaks after a few hours. Unlike Aoba, Ko is a decent cook, and his porridge tastes just the way Wakaba prepared it for Aoba. After Momiji tells Aoba about a time Ko played with her when no one else would, Aoba tells Ko that she will never be a good sister like Wakaba, then gets mad when he tells her she is not that worthless. Ko cooks New Year soba for Momiji and himself, but Aoba makes her own instant noodles. Ko stays the night to watch Momiji and after the three fall asleep while watching television, Aoba snuggles up to him, thinking he is Wakaba. The next morning, before Aoba wakes up, Momiji tells Ko they looked comfortable sleeping together. Ko leaves to practice pitching with Akaishi and Nakanishi, and in a montage, the main cast is shown training as time passes, ending with spring.
Before the prefectural summer tournament begins, Aoba teaches Ko how to throw a slider. Midori asks Aoba to pitch for her high school team in a practice game against Oka University, the current national champions in women's baseball. Aoba refuses, claiming Seishu as a prior commitment. At practice, Aoba overhears some younger Seishu players say her pitches are hard to bat because they want to avoid hitting a girl with the ball. That night, she remembers Wakaba telling her she will pitch at Koshien. After Meano turns down an invitation to play Oka, Aoba watches Oka defeat another high school boys team and agrees to play for Midori's team, Satomi Girl's School. However, the Satomi catcher and team captain, Matsuyama, does not allow Aoba to start as pitcher. In the first inning, the Satomi center fielder is injured and Aoba substitutes for her. When Aoba makes a play for the final out of the inning, she is welcomed by the other team members. At the end of the first, Oka leads 3 to 0.
In the top of the fourth inning, Azuma hits a double but again fails to score. In the bottom of the inning, Mishima stands in the first base coach box, where he tells first-baseman Azuma he is having fun. Akaishi and Aoba are both impressed by Ko's pitching, and the end of six innings, with the score unchanged, Ko has struck out 10 of 18 batters. In the seventh inning, Shimano breaks a finger fielding Azuma's hit and is replaced by Mishima, making Ko and Akaishi worry about Seishu's chances. When Mishama bats, later that inning, he hits a solo home run to tie the game at 1. At the top of the ninth, Senda hits a single, thus ensuring that the best hitters of both teams, Azuma and Mishima, will bat again. As Azuma comes to bat with two outs, Ryuo sends out Oikawa as relief pitcher, and he intentionally walks Azuma before striking out Akaishi. Ko sacrifices control for speed to pitch to Mishima, who manages to hit a blazing line drive that Ko barely catches.Watch Now:Amazon
Ko strikes out the last Ryuo batter, sending the game into extra innings, tied 1 to 1. At the top of the tenth, Ko loses control of his bat before successfully bunting, but is left on base. In the bottom of the inning, after fouling off Ko's fastball, a Ryuo batter loses his bat because his hands are numb from the previous pitch. With a runner on second, Oikawa hits a line drive that Ko, with his arm still affected by Mishima's hit, fails to catch. The runner scores, and Ryuo wins the game. After the game, Ko apologizes to a disappointed Aoba for losing, but she manages to smile. Ryuo goes on to easily win the prefectural tournament and their first game at Koshien. When Ko apologizes to Azuma for failing to make the play, Azuma tells him to focus instead on Aoba's disappointment at not being able to play in tournament games. As Ko and Azuma walk past the construction next-door to Kitamura Sports, they are told by a young woman who resembles Wakaba that it will be a soba restaurant.Watch Now:Amazon
Aoba's teammates ask her out on dates conditional on their performance during a game, but she criticizes their goals as too low. Even with Aoba not pitching her hardest, Seishu Junior High wins in a called game. Afterward Senda meets his cousin, Midori Koganezawa, who is annoyed he ditched practicing with her to watch Aoba's game. Midori challenges Aoba as a batter, but Aoba declines to pitch to her. At the Tsukishima batting cages, Ko tells Midori the pitching machines are not as fast as Aoba's pitches. Ko helps Risa Shido, the spoiled varsity team manager, go shopping and brings her to the Clover Cafe, where he asks Aoba to put the bill on his tab as a birthday favor. Aoba finally agrees to pitch against Midori and strikes her out; she tells Midori she plans to attend Seishu High School, even though she would not be able play in tournament games, instead of a school with a girl's baseball team. Aoba learns from friends that Ko was being Risa's servant for a day in return for the last available teapot that is the 16th birthday gift on Wakaba's schedule of presents.Watch Now:Amazon