My Brother, Who Graduated From Junior High School, Has Become A Hermit Who Doesn't Even Have A Part-time Job Because I, Who Pamper Him So Easily, Affirm Everything And Even Help Him Masturbate. Shizugawa

Shizuka spoils her useless younger brother, who never got a steady job after middle school and just loafs around the house. Their parents have long since given up on him, and he has no ability to live on his own or a girlfriend. His sister, who continues to devote herself to him, even takes care of his intimate needs and still affirms him... All of this is for her brother's sake... What is the true purpose of this abnormal, supportive love?