I'm looking for a shotacon. The protagonist is a middle schooler boy I think; his mother has just remarried and together with them lives his stepfather's brother, that should be a college student. In the beginning you see his mother complaining with her husband about his freeloading brother. The boy doesn't seem to like his new uncle but in reality he is fascinated by him. One day the boy comes home and finds his uncle having sex with a girl in the living room; shocked he runs in his room and remembering the scene he gets hard. His uncle, that had noticed that the boy had seen them, reaches the boy in his room and confesses to him that he had always liked him and that he wanted to wait that he grew up a bit more before confessing but he couldn't resist anymore and so they have sex and become lovers.
It should be a oneshot in a collection. Thanks in advance ^.^

It's chapter 5-6 from Himitsu no Okusuri