Kazuya Kinoshita, a 20-year-old college student, experiences heartbreak when his girlfriend Mami Nanami abruptly ends their relationship. Struggling with loneliness, he decides to alleviate his pain by hiring a rental girlfriend named Chizuru Mizuhara through an online app. Chizuru captivates Kazuya with her beauty and charming personality, and he starts developing feelings for her.
However, when Kazuya discovers negative reviews about Chizuru from other clients, he becomes convinced that her kindness was merely an act to toy with his emotions. Frustrated, Kazuya rates her poorly, triggering a confrontation where Chizuru reveals her true assertive and hot-tempered nature. Before their argument concludes, they receive news that Kazuya's grandmother has been hospitalized.
In a spur of the moment decision, Kazuya introduces Chizuru to his grandmother as his girlfriend, prompting Chizuru to reluctantly play along. As Kazuya grapples with his lingering feelings for his ex-girlfriend Mami, the challenge lies in how long he and Chizuru can maintain their charade as an unlikely couple.