Karyou grew up in the slums and was trained from childhood to kill, making her living as a skilled assassin. Her next target is the emperor Rougetsu, a ruler notorious as a tyrant and cursed emperor who governs the land with a cold, iron fist. Karyou infiltrates his castle intending to complete her mission, but she is swiftly subdued by a perfumed scent the emperor uses, which robs her of her physical freedom. Instead of killing her, Rougetsu takes her as his consort, publicly presenting her as a goddess of good fortune. Trapped in the palace and forced into a contract marriage, Karyou pretends to play along while secretly waiting for a chance to eliminate him. However, as she is repeatedly drawn into intimate encounters with the emperor, her feelings begin to shift from pure hatred to something more conflicted. She starts questioning the meaning of killing him as she witnesses another side of his rule and his own personal struggles. Meanwhile, Rougetsu, who once believed his life existed solely for his people and that he could not afford to die, begins to develop genuine love for Karyou. That realization changes his outlook drastically: he no longer sees himself as expendable. Their relationship evolves amid palace intrigue, power struggles, and the slow unraveling of mutual distrust, creating a Chinese palace fantasy romance where an assassin and a cold emperor are caught between love, duty, and the ghosts of their pasts.