Kiss the Demon Lord

Zhong Ying transmigrates into a cannon fodder female supporting character in a fantasy novel. The original owner was forced to marry the ruthless demon lord, a villain from her half-sister, out of fear of retaliation for her substitution marriage, and committed suicide by jumping into the pool on their wedding night. Determined not to wait for death, Zhong Ying recalls the novel's plot: the demon lord has a fatal weakness; once kissed, he experiences synesthesia with her, meaning he would sacrifice his own life to save her. Zhong Ying decides to seal her fate with a kiss and seek revenge against the evil man.