One day during a casual conversation about romance, a high school boy tells his friends that his ideal girl has long black hair and carries herself well. The very next day, Shimizu, the blonde delinquent who sits next to him, arrives to class with her hair dyed jet black. This sudden and dramatic change marks the beginning of an awkward and heartwarming romance.

The story follows Daiki Hondo, a laid-back and straightforward high school student who seems relatively oblivious to the effect his words have on others, and Shimizu, the tough and intimidating girl who sits beside him. Despite her reputation as a Yankee or delinquent, Shimizu is deeply shy and awkward when it comes to expressing her feelings. Her decision to dye her hair is a direct attempt to become Hondo’s ideal girl, and she continues to transform her behavior based on his casual remarks.

The setting is a typical Japanese high school, providing the backdrop for their daily interactions. A key narrative driver is Hondo's seemingly innocent conversations with his friends. When he mentions a trait he finds appealing, Shimizu immediately tries to adopt it. For example, after Hondo talks about wishing a girl could cook for him, Shimizu, who previously skipped class, partners with him in cooking class and begins packing him homemade lunches. Another major theme is Hondo’s consistent denseness; he compliments Shimizu openly and honestly, calling her cute or beautiful, which causes her to blush and become flustered, yet he often fails to realize that her actions are a direct result of her growing feelings for him. The story builds on this series of misinterpreted signals and earnest, clumsy efforts, creating a sweet and comedic dynamic as the school’s most intimidating girl tries her best to win the heart of the most straightforward boy.