Kazuya Kinoshita, a 20-year-old university student, enjoyed a happy relationship with the lively and cheerful Mami Nanami until she abruptly broke up with him, leaving Kazuya heartbroken and adrift. To cope with his loneliness, he turns to an online app to hire a rental girlfriend, where he meets Chizuru Mizuhara, whose striking beauty and adorable personality immediately catch his attention. However, after reading reviews from other clients who had similar experiences with Chizuru, Kazuya starts to suspect that her kind smile and affectionate behavior are just part of the job, designed to play with his emotions. He decides to give her a poor rating, which enrages Chizuru and leads to a heated confrontation where her true sharp and passionate nature comes out. Their argument is interrupted when Kazuya learns that his grandmother has fallen ill. Rushing to the hospital, they find his grandmother already recovering, but confused by Chizuru's presence, she asks who he is. On impulse, Kazuya claims they are lovers, forcing Chizuru to keep up the act. With Kazuya still fixated on his ex-girlfriend Mami, how long can this difficult client and unwilling rental girlfriend maintain the deception?