[Sawajiri Merou] H na Imouto Mao wa Haramitai! [Digital]

When the demon finally gets pregnant she steals the baby to the demon world and the siblings go back to normal. Sister can’t stand that her baby was stolen so she summons the demon again to inhabit her body again . The demon separates herself though and the brother gets them both pregnant this time. The end

So, the story. Dude summons a demon, she inhabits his sister’s body and won’t leave until she has his baby. She and the sister keep swapping depending on who is in control of the body. Demon is incredibly horny all the time and she makes a womb tattoo to ensure the sister gets pregnant.

When the translation

I glanced through this without looking at the tags. That's his sister?!

怎麼沒有跟女兒大戰一場的劇情?