Lord Lu Just Wants My Mermaid Tail

(I thought I had transmigrated into the original novel, but it turns out this damn thing is a fanfic!) Tang Li discovers that she has transmigrated into a book and become a cannon-fodder heiress on the verge of bankruptcy. With all the death flags she's raised, her ending is bound to be tragic. But Tang Li isn't worried at all. As long as I stay away from the melodramatic male and female leads, I'll still be on top! Later, she finds that she drops pearls whenever she cries and grows a beautiful mermaid tail whenever she touches water. Tang Li is... even more excited. No one knows that the frail young master of the Lu family has two personalities: one a saintly do-gooder, the other a tyrant. One day, the tyrant gets hit by a fool called the System. System: Countdown to death. You must confess your love to your destined partner. Your speech must be at least five hundred words. The tyrant at first: Who the hell are you? Later. Wearing the saintly personality, the tyrant corners someone in the bathtub and gently coaxes, “Be a good girl, Little Li. Let me see your tail.” Later still. Wearing the tyrant's personality, the saintly one drives someone onto the bed, his eyes wild as a beast's. “Little Li, why are you running away when you've been so naughty?” Faced with such a split-personality male supporting character, Tang Li clutches her beautiful tail and trembles. “Who are you people!”