Mikotonori! ~Imouto Miko to Nakadashi Jorei~

In a quiet countryside town lived the Kuou siblings, exorcists by trade. Mizuki Kuou, the younger sister, dressed in shrine maiden attire, specialized in directly purifying evil spirits. Seishirou Kuou, the older brother, lacked strong exorcism abilities but made up for it with sharp intuition and supportive techniques to back up his sister. Together, their seamless teamwork made them an unstoppable duo—no evil spirit stood a chance against them! …Or so they thought. "Ugh…! I let my guard down… My body… it’s so hot…!" A lust-driven evil spirit had somehow possessed Mizuki’s womb! To make matters worse, completely eradicating this spirit required—for some reason—Seishirou’s potent DNA. Now, with Mizuki transformed into a wildly aroused and uncontrollable mess, the only one who could calm her down was her brother (and his sperm)! And so, to banish the evil spirit and save his sister… The "Exorcism by Creampie" begins…!! [Translated from dlsite]