“Won’t you become my fiancée?” Restarting life from rock bottom by becoming the fiancée of an arrogant heir!? Shino Maisaki, who works at a major company, has low self-esteem due to her upbringing. Even so, she has been dating her department head, Naoki Mizushino, for a year. However, for some reason, the candidate for Naoki’s fiancée turns out to be none other than Shino’s younger sister, Himari!! To make matters worse, at work rumors spread that Shino and Naoki broke up because Shino cheated, putting her in a desperate situation. At that moment, the one who approaches Shino with a proposal is Masayuki Mizushino—Naoki’s older brother and an executive director at the company. Masayuki is rumored to have a difficult personality, but unlike others, he doesn’t flatter anyone and speaks his mind. Through this “contract” with Masayuki, Shino’s life begins to change dramatically…!