Adult PC Game: Aniyome - Miboujin - by Atelier Sakura Archive

When Mitsuru was young, his older brother took care of him and he viewed him like a foster father. One day, his brother suddenly dies, leaving behind his wife, Kitadate Yura and their newborn daughter. Since his brother took care of him all the time, he wants to return that to his family and support his widowed sister-in-law and niece, but after some time he starts to view Yura as a woman and he wants to start a family with her.