Fifteen-year-old Kei is chronically unlucky in love. She has been best friends with Yumi since childhood, and the two live next door and attend the same school. The problem is that Yumi is tall, elegant, and effortlessly beautiful, and every boy Kei develops a crush on ends up falling for Yumi instead. Her latest heartbreak comes when she loses Minami, a fun-loving filmmaker and musician she admires, to Yumi. Kei sinks into depression, convinced she can never compete.

One night at a dance club, Kei is miserably watching Minami and Yumi together when a mysterious DJ catches everyone’s attention. The man leaves the booth, walks up to Kei, and gives her a quick makeover, changing her hair and makeup. To her shock, she realizes he is Hirama-sensei, the dorky, glasses-wearing science teacher at her school. In the club he is cool and stylish, a complete contrast to his school persona. He explains that his club appearance was part of an experiment, and then he proposes a new one: he wants to transform Kei into a playgirl, a confident and attractive young woman who can steal Minami away from Yumi. Kei, desperate and intrigued, agrees to become his test subject.

As the experiment unfolds, Kei begins to change her appearance and attitude, but the situation grows complicated. Yumi’s motives become suspect—she may be deliberately stealing Kei’s crushes. Meanwhile, Hirama-sensei’s own feelings become unclear, and a love square forms among Kei, Minami, Yumi, and the teacher. The story follows Kei’s romantic misadventures and her struggle to define her own worth beyond comparisons to her friend, all set within a high-school and after-school club scene. The series balances comedy and romance, with Kei’s transformation and the shifting relationships driving the narrative through seven volumes.