Tianna, a court pharmacist, has been in love with Crown Prince Saphir since she was a student. She chose to become a court pharmacist not only because she wanted to help others, but also because she wished to be close to Prince Saphir, even if her love could not be fulfilled. Her eight-year love was supposed to have ended when Saphir was crowned emperor and became an agent of God. Tianna decided to put her feelings to rest and devote herself to her work. Then, a special mark appears on her, indicating that she is the emperor's "mate."