High school girl Erika may be on Kyoya's leash, but she's determined to break free and unleash his heart! Fed up with being hopelessly single, high schooler Erika makes up a boyfriend to fit in. When her lies start to unravel, her schoolmate Kyoya offers to be her pretend boyfriend--for a price. With no other choice, Erika finds herself at the mercy of a blackhearted prince! But is Kyoya truly as blackhearted as he seems? Kyoya goes full sadist mode when he's tasked with tutoring Erika's little cousin Lena, a headstrong, smart-aleck middle schooler. But Lena appreciates Kyoya's tough love approach, and later, when he saves her from a scrape in a bookstore, she suddenly finds herself head over heels! How will Kyoya and Erika get out of this one?!