The shopping center's baseball team and the city's team schedule a match to decide who may host the festival. As the head coach for some reason, Meme decides to sub Erio in as the pitcher. Meanwhile, Makoto must seek out Maekawa-san's AWOL father.
It's summer vacation, and Makoto doesn't have much to do, so he accepts an invite to play baseball with Maekawa-san. After one game, Erio hears about Makoto's ballplaying and insists that she wants to play, too.
One month ago, Maekawa-san received five plastic soda bottles. When she confronts the man who gave them to her, he asks Maekawa-san to build plastic bottle rockets for him. After being offered 5,000 yen per rocket, Maekawa-san accepts.
Ryuuko rediscovers Erio's infamy. She is worried that Makoto might get ostracized at school because of Erio's past. Also, Maekawa-san decides to visit Makoto's place. Ryuuko, who has conflicted feelings for Makoto, begins to show signs of irritation.
Meme freets about her 40th birthday, but a gift from Erio spurs her to celebrate Erio's birthday the next day, since they skipped it when it actually came about. Erio tells Makoto she wants to rejoin society.
Erio, despite her beautiful appearance, is a strange girl who believes herself to be an alien. One night, Erio asks to be taken to a distant beach, where Makoto learns about the incident that caused Erio to begin calling herself an alien.
When Niwa Makoto's parents move overseas, they decide he would move to the city and stay with his aunt, Towa Meme. Makoto's been told that Meme is unmarried and childless, but when he arrives, he finds a mysterious girl wrapped up in a futon.