(Disclaimer: This is how I remember I'm too lazy to meticulously cross reference everything so there might be some errors, but it should be mostly correct.)

The main characters for this chapter are, in order of appearance: 浅羽直之 (Naoyuki Asaba), 伊里野加奈 (Kana Iriya), 榎本 (Enomoto), 水水前寺邦博 (Kunihiro Suizenji), 須藤晶穂 (Akiho Sudou), 椎名真由美 (Mayumi Shiina), and 浅羽夕子 (Yuuko Asaba). The story takes place in 園原 (Sonohara), a small country town that has an airbase.

1. 第三種接近遭遇 (Close Encounter of the Third Kind): Hearing from Suizenji that it's feels good, on the last night of summer before the start of the semester, Asaba sneaks into the school's pool for a dip where he finds a mysterious young girl, Kana Iriya, who has a round dome on her wrist. After startling her and ending up teaching her how to swim, she gets taken away by another mysterious man (Enomoto) who claims that he's like her brother.

Flashback to the beginning of summer where Suizenji, a tall, popular (with the girls), and a bit eccentric guy who aspires to work for the CIA has the idea that he and Asaba, who along with Akiho make up the journalism club at school, has the idea that they should camp out in the mountains. He's fascinated with UFOs and at times at odds with Akiho because of his interests. While Suizenji stays there the whole time, Asaba comes home every-so-often during the summer.

Flashback to current time where it's the first day of school and there's a new student in class, Kana Iriya.

2. ラブレター (Love Letter): Asaba has thoughts that she's an alien coming to take over the world. However, her story is that she's just returned to Japan and is living with her brother on the base. She wears some conspicuous wristbands. When some of the girls in class try to befriend her, she tells them to go away. When Asaba notices that she's spotted him, he decides to go to the bathroom. Akiho follows him there and talks to him once he comes out. She knows that he had met her previously as he asked her about the school's female swimsuits. He suddenly feels lightheaded and passes out. When he wakes up, he's in Mayumi's office, the nurse. Mayumi has him rest in the office and gives him some sedatives. When Akiho leaves, Mayumi places a call and Asaba hears something about someone giving him a dose of something last night.

When he's finally out of nurses office, he goes into homeroom and notices that no one is around. He decides to fumble through Iriya's bad and finds some strange items with strange letterings on them. In particular, he finds a telephone card-like item and pockets it. However, he gets caught red-handed when Iriya shows up behind him. She then gets called away to the teacher's office. After school, Suizenji gets really excited when Asaba tells him about this new girl as she lives on the airbase. The next morning, Suizenji makes an appearance in Asaba's classroom and gives Iriya flowers and invites her to the journalism club.

Later that day, the air sirens sound. Asaba's pretty sure that it's just a drill, but Iriya freaks out. She takes him into the shelter, uses the strange telephone card, changes the codes, and arms Asaba and herself. Iriya mentions that "the war has already started. It's just that no one knows about it." While they're inside, they get a phone call from Enomoto who says that it was only a drill and they'll need some time to unlock their way inside to rescue him. Iriya finally calms down. While they're waiting, he asks her about the gaming device that she has and she teaches him how to play the simulator. Suddenly, she has a spasm and Asaba calls Enomoto for help. He tells him that she needs to be injected in the heart and there should be a mark on her chest where he should stab when he takes off her clothes. Just as he's about to do so, the shelter door opens.

A few days later, he receives a note in his locker. He thinks it's a love letter, but in fact, it's just a notice saying that Iriya wants to join the journalism club. For the reason though, she writes "Because Asaba is there."

3. 正しい原チャリの盗み方 (How to Properly Steal a Mini-bike): The weekend after their first week, Asaba is going to go out on a date with Iriya. The way this came about was that Suizenji has this brilliant idea that if Asaba can get close to Iriya, maybe she will talk, so he has him ask to go to a movie with Iriya.

Yuuko, Asaba's little sister who has no respect for his brother woke him up that morning and noticed that he was acting a little different so he looks around his room and finds a magazine with a movie and time circled. She then finds Iriya's club-entrance notice and sees why she wants to join. Yuuko can't believe it so she follows after her brother.

Outside the theather, Enomoto and Mayumi are spying. Yuuko bumps into Suizenji who are also spying on the new couple. When they enter the movie theater, the two groups follow, not knowing that they're both trying to listen in. Suizenji has bugged Asaba so he can listen in on his conversations. Enomoto gets a call with info that there's been some strange radio activity in the area. He looks over and thinks he sees Suizenji. Suizenji leaves for the bathroom and comes back, sitting on the other side of Yuuko. Enomoto knows he's been spotted and drags Mayumi out. Suizenji also knows about them now and he chases them out of the theater taking pictures of them. Asaba looks back at the ruckus and soon after, the movie is halted.

Bonus. そんなことだから (It's Because of That...): Mayumi has just moved into her new apartment and is going to start her new job as school nurse in three days. Just as she moved in, Enomoto calls her and has her watch a TV show where the guests are talking UFOs. Enomoto has a good laugh while watching, but then the TV show hosts get a fax from the Sonohara school newspaper about canisters with alien bodies inside. He freaks out and Mayumi sees that soon after, the hosts are at the base with their cameras demanding to see the canisters. It turns out that they're just dummies. However, since them, Mayumi remembers the school newspaper.