Sacrificed to the Abyss, Crowned by the Dragon

Pure-blooded golden-tailed mermaid Eve is betrayed by her stepsister, fiancé, and father—but after rebirth, she leaps into the abyss as a sacrifice and awakens the poisoned Abyss Sovereign, Leviathan, with her divine blood. To avenge her mother and survive a hundred-thousand-strong army and the Sea Queen's schemes, she must rip out her own heart to save him and pass the Ancestral Dragon Trial—rising from abandoned "fake golden tail" to godhood and reclaiming her crown.