Among the nobles yearning for true love, a select few are fortunate to receive an invitation to join the Jewel Box. In a secret magical place, noble men and women take on new appearances and don the names of jewels corresponding to their personalities. They can get to know one another and compete for time alone with the participants who have struck their fancy. However, they must not reveal their true identities until they have found their perfect match.

The recently wed Lueri Lyza detests her arranged marriage to an unkind husband. When she is unexpectedly invited to the Jewel Box despite her marital status, a mysterious man going by "Moon Owl" asks her to take the place of Marianne Farie Sieris—a free-spirited former participant who once captivated the audience. Marianne was hoping to find love again in the Jewel Box after her husband's death, but she has suddenly vanished, and the show's broadcast must go on without the public finding out.

As the ultimate game of delicate deception and high-stakes dalliance begins to unravel, Lueri puts on her best Marianne act under the alias "Obsidian"—but she might still fall for a gentleman ready to love her true self.