Aniyome ~Nee-san wa Ore no Mono~ by Kannazuki Seikakusho Tsumami Gumi - Adult Sex Game

Take by force, rape and impregnate the wife of a brother who does not respect you!
The main character Takumi is a ronin. He lives at home with his parents and older brother.
His older brother is a good student, and he always had complexes about being compared to his older brother.
One day, the older brother marries and moves in with him. His wife is also a beautiful woman, which further strengthens his complexes.
Takumi feels awkward, partly because he is a ronin.
His sister-in-law, Ayumi, treats him like a .

Meanwhile, their parents go on a trip abroad to celebrate their father's retirement.
Takumi's brother and sister-in-law's nightly activities intensify, and the sound of their voices stirs his imagination, making it difficult to focus on his studies.
One day, Takumi returns home from prep school earlier than planned.
He finds Ayumi's shoes at the entrance and it appears that she is at home. However, his call "I'm home" was not answered.
Suspicious, he turns his attention to the kitchen, where he assumes Ayumi is.
As she carefully opens the door, Takumi's eyes are greeted by the sight of Ayumi masturbating in the kitchen in an apron full of vegetables.