After capturing one hundred secret photographs and observing him from a distance for months, second-year high school student Yuki Kurihara has finally gathered the courage to ask out her first-year crush, Shinya "Momo" Momotsuki. Although caught off guard, the shy Momo agrees; however, he remains ignorant of the deeply abnormal reality. As her strict friend, Norika Mizuyama, has noticed, Yuki has cultivated some unsettling—yet nonetheless genuine—habits: secretly photographing Momo, conducting extensive research into his private life, collecting his used straws, and even engaging in "Momo watching." While Momo remains blissfully unaware of his new girlfriend's peculiar habits, he does detect some strangeness in their daily conversations. Still uncertain and anxious about his first relationship, Momo frequently finds himself in awkward situations due to his inexperience, but he nonetheless resolves to make his new girlfriend happy. Momokuri follows Yuki and Momo as they timidly explore their newfound love, and also address the problems that arise from it.