Plot
Following their summer vacation, Futaro Uesugi and the Nakano quintuplets Ichika, Nino, Miku, Yotsuba, and Itsuki, now third-year high school students, prepare for the upcoming school festival. On the day of the festival, Futaro invites the quintuplets to a room and confesses his love to them, but he tells them to wait until the end of the festival to know whom he has chosen among them. During her acting work on the second day of the festival, Ichika learns that one of her sisters has collapsed and rushes to a hospital, where she sees Futaro and Nino visiting. Ichika strolls outside with Futaro, during which she kisses him at a park. On the second day of the festival, Nino is expecting the quintuplets' father Maruo to visit the school but is unable to find him among the crowd. Futaro approaches her with a video confirming her father's attendance. Nino and Futaro visit her father in the hospital, where she cooks a pancake for him. After the successful meeting, Nino kisses Futaro and thanks her father for choosing him as the quintuplets' tutor.
On the first day of the festival, Miku is accompanied by Futaro in approaching the boys' takoyaki stand, where she promises that the girls supporting the pancake stand are going to enjoy their food. Later, Miku returns to the stand with the girls but finds the place on fire. On the third day of the festival, Miku invites Futaro to a rooftop, where they find two of their classmates arguing about the takoyaki stand incident. After reprimanding her classmates, Miku confronts Futaro out of jealousy from his meeting with an unknown girl yesterday and kisses him. Since the start of the festival, Yotsuba is overworking in helping different clubs. On the second day of the festival, she collapses due to exhaustion. While in a hospital, Yotsuba learns from Futaro that some of the students she has helped before offered their assistance during her absence. On the third day of the festival, Yotsuba kisses a resting Futaro. Itsuki is studying on the first day of the festival when her teacher Mudō reveals his history with her mother. The next day, she learns that Mudō is the quintuplets' biological father and gets angry at him for leaving her mother alone when she was pregnant. On the third day of the festival, Futaro visits Itsuki in the house and motivates her to keep on following her dream of being a teacher. Later, Maruo, Futaro's father Isanari, and Miku (disguised as Itsuki) meet with Mudō. Itsuki tells Mudō that he is not suitable to be the quintuplets' father after failing to see through Miku's disguise.
At the end of the festival, the quintuplets advise Futaro to approach one of them, currently separated from each other in a building, as his way of confession. Futaro meets with Yotsuba and confesses his love, but she rejects him as she sees herself as unfit for him. As she runs away from him, Yotsuba recalls her first meeting with Futaro and the promise they made to each other. In the end, Futaro catches up to her and manages to convince her and confess her true feelings toward him. Yotsuba decides to address the feelings of her sisters first before dating Futaro. After reconciling with her sisters, Yotsuba begins dating Futaro, during which he suddenly proposes to her for marriage at the park with a swing they visited before. Five years later, Nino and Miku, now owners of a cafe, reunite with Ichika, an actress, Itsuki, a teacher, and Yotsuba, who is about to get married. As a wedding gift, Yotsuba's ears get pierced to wear her mother's earrings. On the day of the wedding, the quintuplets play their final game to Futaro, in which he needs to guess who the bride among them is, but he instead identifies them one by one. After the success of the wedding, the quintuplets discuss the best country for the newlywed's honeymoon.
