Hatori Matsuzaki Mirei Kiritani is a colorful freshman high school student who has harboured a deep crush on her childhood friend, the aloof Rita Terasaka Kento Yamazaki. She believes there is no one else more suited to be Rita’s heroine than herself, and she is content simply being his friend. But her certainty shatters when Rita begins a serious relationship with the bespectacled, awkward Miho Adachi Miwako Wagatsuma. Hatori makes several attempts to thwart their budding romance, clinging to the hope that she can preserve Rita’s closeness. When she can’t hide her feelings any longer, she confesses to Rita, only to be rejected. Around this time, she also meets Kosuke Hiromitsu Kentaro Sakaguchi, a playful womanizer who notices that Rita cares for Hatori and starts a casual arrangement with her to irritate Rita, but gradually falls for Hatori. Meanwhile, Adachi travels abroad for three months to pursue journalism.
At a late-summer festival, Rita realizes his growing feelings for Hatori and shares a kiss with her, sparking a real romance between them. They begin dating, but Adachi returns earlier than expected. The news of the kiss hits hard: Adachi is heartbroken and, a few days later, collapses from anemia. Rita, driven by guilt, ends the romance with Hatori and decides to stay with Adachi. This turn of events leaves Hatori distressed, and she resolves to forget Rita by turning her attention toward a deeper relationship with Hiromitsu.
Although she initially resolves to stay with Adachi, Rita finds it increasingly difficult to forget Hatori and ultimately ends things with Adachi, who stops coming to school. Hatori discovers she genuinely cares for Hiromitsu and enjoys being with him, but she cannot stop thinking about Rita and grows jealous when her best friend, Kyoko Nakajima Ayano Fukuda, becomes close with Rita, which strains her relationship with Hiromitsu. Rita resolves to stop being half-hearted and begins to pursue Hatori seriously, confusing her further. Things become more complicated when Hiromitsu starts working part-time with an upperclassman who develops feelings for him, causing Hatori to become bitter and jealous. Hiromitsu, increasingly exasperated with Hatori, breaks up with her, unable to cope with her insecurity and her involvement with Rita.
At the same time, Adachi returns, now a carefree flirt in a string of casual relationships. Rita decides once again to stand by Adachi out of guilt. Hatori, disappointed by Rita’s sudden disinterest, resolves to stay single and forget about her previous relationships, but after a talk with her mother she realizes that she still loves Rita. Hiromitsu, encouraged by a pep talk from his cousin, tries to rekindle his relationship with Hatori, but she carefully rejects him. Hatori pursues Rita and publicly confesses to him once more. Rita is initially hesitant to leave Adachi, but Adachi reassures him that she will be fine on her own. In the end, Rita and Hatori reunite and become a couple, having weathered a tangle of feelings, misunderstandings, and interruptions that tested their connection and ultimately brought them back together.
