The protagonist, whose name is not revealed in these chapters, is dumped by his girlfriend of one year, Makimiya Airu. He learns that their entire relationship, including her confession, was a punishment game from a rock-paper-scissors match. Initially shocked and then amused by the absurdity of the situation, he processes the breakup with a mix of anger and lingering affection for Airu, recalling their pleasant, albeit physically restrained, relationship.
Returning home, he encounters a girl sitting in front of his apartment. She introduces herself as Hanazono Koume, his childhood friend whom he hasn't seen in ten years. Koume has moved to Tokyo for high school and, due to her guardian, Rei-chan's, concern for the protagonist's living habits, has come to live with him. The protagonist is surprised by Koume's sudden appearance and her immediate assumption of a caretaker role, noting her transformation into a beautiful young woman.
Koume quickly takes charge of the protagonist's neglected household, finding his refrigerator empty except for water. She begins to cook for him, preparing his favorite tonkatsu, and they establish a routine of shared meals and household chores. The protagonist finds comfort in Koume's presence, which helps him cope with the breakup. He also discovers that Rei-chan, his aunt and guardian, has left her room for Koume to use, though it is in a state of extreme disarray. Together, they clean Rei-chan's room, preparing it for Koume.
The narrative then shifts to the protagonist's first day of high school. He is reunited with his friend Kisaragi, who notices a positive change in the protagonist's demeanor. Kisaragi reveals he has a new girlfriend, Akane Yuzuki, whom he met on Instagram and initially believed to be older.
At the school entrance ceremony, Koume attracts a crowd due to her beauty. The protagonist intervenes when she appears overwhelmed by attention from upperclassmen, leading to a misunderstanding that they are a couple. Later, at a family restaurant, it is revealed that Kisaragi's girlfriend, Yuzuki, is actually younger than him, having lied about her age. The group, now including Koume and Yuzuki, discusses their relationships and living situations. Koume and Yuzuki quickly bond, exchanging contact information.
The protagonist also learns that Koume has a hidden past, evidenced by scars on her left wrist, which she is reluctant to discuss. The chapters conclude with the start of the new school year, with Koume attending a nearby all-girls school, Seiran Jogakuin. The protagonist continues to navigate his life with Koume now living with him, finding a new sense of normalcy and support amidst the lingering feelings from his breakup.
