La Heredera de la Isla del Destierro que Ellos Subestimaron

Abby grows up on the Exile Island, raised by a group of secret legendary powerhouses. Her long-lost Count father brings her back to the imperial capital to be a substitute bride for the abyss-cursed Duke Blake, replacing his adopted daughter Lillian. Abby reveals her extraordinary talents, lifts Blake's curse with a lost potion, and grows close to him. When Lillian stages a coup and unleashes a monster horde, the island elders arrive to crush the rebellion. Abby marries Blake and finally lives her ideal life.