Profligate heir Leo Voss accidentally swaps bodies with Princess Luna Sterling, the bullied princess. Leo binds to the Empress System, with swaps every ten days. As Luna, Leo confronts bully Mabel, exposes Consort Lila's plot, wins the emperor's favor, and advances toward empress. As Leo, Luna sheds his profligate image, studies, trains, passes exams, and restores Dingyuan Manor. They support each other, develop romantic feelings amid swaps, fending off schemes while rising in status.