H na Imouto Maou wa Haramitai!

I love my sister Himeko!
I want to have sex with Himeko!
Okay, I'll use black magic to make my wish come true!
I tried to summon a demon, but to my surprise, "Anastasia", the otherworldly demon king, was summoned!
This is the demon king with an erotic body, but she has possessed my sister and made a contract with her to procreate!
I must impregnate my sister (the Demon King)!
I can have vaginal ejaculation with my sister Himeko!
Wishes come true when you think about it!

(Source: Comic Mujin, translated)

Note: Includes one extra chapter.