My love from the mortuary

When a monster is tasked with acquiring the moonstone that will save his descendant and make him powerful. Yet to regain Moonstone’s power, he has to make sure that the girl of “Reth descendent” loves him since she is the protector of Moonstone, and after that, in any case, he has to kill her. But what will happen when he approaches the girl and realizes she is the girl he loved before he died? Will he kill her, or will the delinquency feeling compel him again to love her?