Harehi is a high school girl with a severe sister complex: protecting her adorable younger sister Hinata from any male attention is her top priority, and she has no interest in romance for herself. One morning during the crowded commute to school, she gets into a tight spot on the train and is rescued by a stunningly handsome stranger. Before she can thank him, he disappears into the crowd. To her surprise, she later discovers he is a new transfer student at her school—and the grandson of the neighbor her own grandfather has strictly forbidden her from interacting with. His name is Hanakaze-kun.

Despite the family hostility, Hanakaze-kun is an incredibly gentle and popular boy, but his popularity has made him uncomfortable around women. To fend off his persistent admirers, he asks Harehi to pose as his girlfriend. She reluctantly agrees, partly out of gratitude and partly to keep an eye on him for her grandfather’s sake. Their fake relationship quickly becomes complicated: the more time they spend together, the more genuine their feelings grow. Harehi, who has always prioritized her sister over herself, finds herself developing real romantic feelings, while Hanakaze-kun, though socially awkward, treats her with surprising warmth and honesty.

The series traces the pair’s journey through a series of obstacles: school trips, misunderstandings about other love interests, the nosy attention of classmates, and, most significantly, the deep-seated feud between their grandfathers. The mystery of why the two old men despise each other lingers in the background, threatening to tear the couple apart. As Harehi’s feelings finally overflow, Hanakaze-kun responds in turn, and the two confess their love. But even after they become a real couple, they must still confront the strongest barrier—her grandfather’s opposition. The story concludes as they fight to overcome that final hurdle, bringing their heartwarming, awkward romance to a close.