Onee-san to Amaero Milk Kissa ~Shibotte Nonde Ippai Nakadashi Shite ne♪~

The main character runs a coffee shop with his older brother. His brother gets married to a girl, Sayaka, and they live together. But one day, his brother suddenly passes away.... He decides to take care of Sayaka, who is now pregnant, until she gives birth. After she successfully gives birth a baby, he visits a shrine to pay homage. But he accidentally breaks a shrine building. Now that he is cursed by an evil spirit, he can drink only mother's milk. Sayaka knows it and offers her milk to him. Also, she helps him get rid of the curse, which will be done by ejaculating.

[From ErogeShop]