Lilia Pregnant The World End summary:

“The world will be destroyed if you have sex with the Demon King's daughter.”After defeating the Demon King and saving the other world, the hero Takahiro returns to the real world. One day, Lilia, the daughter of the Demon King, suddenly arrives at Takahiro's place, where he leads a peaceful life. Takahiro braces himself for revenge, but her goal is to bear the strong Takahiro's child…!?