One Day My Sister Died

My sister, who was sold off from the Pellier mansion, returned dead after becoming the bride of the monstrous, dethroned prince. And now... I am next. The ninth bride of the dethroned prince, heading to that black mansion. "And after the first night?" "After we spend our first night together, you won't be able to cast me out, even if you wish to, Your Highness?" In this dark mansion, where the monstrous prince who may have killed my sister resides, I will survive, seeking the truth of my sister's death. No matter what it takes.