Haitoku no Kakure Boseiai -Yasashi Sugiru Ecchi na Onee-san wa Okaa-san! | 背徳の隠れ母性愛～優しすぎるエッチなお姉さんはお母さん！？～

A mother who left him when he was a child and is no longer known where she is. After a lot of research, I finally found this town. Takuma, who started to live alone, using his body to commute to school.

He has a woman he met since he moved here and can take care of her. That person is Fuyumi-san. She was a older sister who lived in the neighborhood and took care of my daily needs. And then, "Takuma" realizes that he has more than just admiration for her. Furthermore, he wants to cross the line and he starts to act out.

However, after this, he will know the truth. She...