Yume and Mizuto are home alone in the middle of a typhoon, reading alone in their respective rooms, when Yume encounters a cockroach, which renders her room no longer habitable. The two top students in their grade, neither of whom are particular fans of bugs, decide the only option is to sleep together in his bed.
While they start out back-to-back, Yume eventually shifts positions in her sleep, and when Mizuto wakes up and rolls over, he finds himself closer to Yume’s face than he’s been in a long time (not counting that recent time on the couch). He rolls back over, saying he has no room for “lingering feelings” in their new life together.
The next morning, Yume and Mizuto unconsciously act like a couple going through a rough patch, leading their parents to make that observation. Yume’s mom also suggests Mizuto buy a swimsuit for the upcoming family trip to Mizuto’s dad’s riverside hometown.
For their parents’ sake, the former couple proceeds with the swimsuit-shopping trip, and while Yume tries to “disguise” herself with the same glasses she wore in middle school, the fact she’s wearing her new, more form-fitting style would certainly give her away to, say, Akatsuki.
Mizuto waits outside the changing area, somehow not expecting Yume to show him the cute frilly pink bikini she’s trying on…but she does. When he says it merely looks “good” on her, “he thinks”, she asks him to say something nicer, and so…he compliments her devotion to her family.
On their way home they pass by the very quiet side street where they kissed for the first time, at the very same time of day. When the wind knocks Yume’s hat off, Mizuto naturally lunges toward her, resulting in the two ending up in a very similar position to that magical day.
Yume even closes her eyes and prepares her lips for another kiss, seemingly overcome by the atmosphere…but Mizuto hesitates. Later at home, Mizuto and Yume converse awkwardly, trying to keep up appearances, leading their folks to remark how they’re like “a couple working up the nerve to pop the question”.
While it seems like their parents are oddly perceptive, the fact is neither Mizuto’s dad nor Yume’s mom have any idea about their real past. That’s probably for the best, as considering how nice they both seem, it would pain them to know end to know their marriage inadvertently put their kids in such a strange, even cruel situation.
Speaking of cruel, when Isana comes over for the umpeenth time during summer break to watch a movie with Mizuto, she reclines on the couch, rests her head in Mizuto’s lap as he strokes her hair. They’re a picture of a couple destined for a fifty year-plus marriage, so comfortable Isana thinks nothing of scratching around her bra area in his presence.
After the movie Isana gets up, but continues to monopolize Mizuto by engaging in a lively critical conversation in which Yume cannot hope to participate. When Mizuto asks for tea without saying please, Yume serves him some…in her mug, which Isana immediately identifies as an indirect kiss.
The movie and discussion cause Mizuto to suddenly nod off, but rather than falling into Isana’s lap, his head falls into Yume’s. Isana briefly considers kissing him since the opportunity is there, but as it would be her first kiss and Yume is right there, she wisely thinks better of it. How horny is this girl?!
Looking down at the sleeping Mizuto in her lap, she realizes why he hesitated, both when they were in the same bed and when they almost kissed in their first kiss place: they both feel the same longing for the way things were, and wanting to go back to those times, but believing it not worth destroying the new life they have together.
Later, Yume’s mom wants details about what’s up with Mizuto and Isana (who earlier said she wouldn’t mind being fuck-buddies or FWB with him). Isana indulges her mom, who then tells Yume she can’t let Mizuto leave her behind; she needs to find a boyfriend for herself.
While lying in bed contemplating her mom’s words about getting a boyfriend, Yume says, out loud, that she doesn’t see herself with anyone but Mizuto, which surprises her. So far, the two have maintained the position that they can’t go back to the way things were, but that’s increasingly easier said than done.