In order to repay her parents' debt, Haruka ends up being sold to the Azumi family as collateral and forced to take care of Yukiya, the young master of the Azumi family. At first, Haruka is confused by the boy's actions, but as they continue to live together, they become closer and she begins to sympathize with the boy's loneliness. One day, Yukiya proposes to make Haruka his wife. Although shocked by the sudden proposal, Haruka promptly brushes the matter to the side and promises to reply when he grows up. She thought it was just a childish promise... Time passes, and the boy grows into a remarkable young man. He still harbors romantic feelings for Haruka, but she continues to run away, thinking that she is not worthy of him. However, when she sees him talking intimately with another man, the young man's obsession and jealousy grows...