Yuuta feels lonely because his mother only cares for his sickly younger brother. One day, Yuuta witnesses his mother masturbating and forces a sexual relationship with her as a way to get her attention towards him. However, when their relationship is discovered by his younger brother, he begs his mother to perform lewd acts on him, saying that he too is sick and does not know the female body. And so begins the obscene nursing of his brothers by his devoted mother...