the tyrant's replacement bride

Sebastian Leodegrance was fated to bring about the world's end, his path irrevocably marked by the three scars etched across his left eye as proof of his unholy contract with Ardalas, the Evil God. His insatiable thirst for power would have been enough to conquer all, even without the infernal blessing, but now not even the divine intervention of the Goddess could thwart his ambitions. With purposeful strides, he marched toward Cassiopeia to claim the hand of the renowned Princess Ava Cassia, a woman whose veins coursed with the blood of greatness. But as he drew closer, he discovered that the Princess had been exchanged with her Lady in Waiting. "Yes. I am the replacement. You have been fooled!" *** "From now on, Isla, call me Elder Sister." The person in front of her was the brightest constellation in the world. Ava Cassia... the Princess who was even prettier than the Nereids. But it was like looking in the mirror. She looked exactly like her. "Maybe the Goddess sent you to me so we can become Sisters. How about it, my dear Isla? Would you call me Sister?" Her most cherished treasure; her Elder Sister, Ava. "I'm sorry, Sister... this is the only way." "You must replace me. Because if I bear his child... this world would perish..."