The narrative of Marriage Royale centers on Tsukasa Hinomoto, a high school student who learns from his parents that he was adopted. They further reveal that his biological father is a manager at a major corporation, indicating he possesses significant wealth and influence. Seeking a suitable wife for his son, Tsukasa's father organizes Marriage Royale, an event where attractive women from across Japan gather at a school constructed specifically for this purpose to compete for the role of Tsukasa's fiancée. This school is situated on a secluded island off the coast of Japan, where Tsukasa resides in a mansion under the care of twin maids: Miku, the older sister, and Miu, the younger sister.