GVG-544 My Big Sister's Real Sex Education

Haruka is an older sister who dotes on her younger brother. However, one day her younger brother starts saying "Let's have sex!" repeatedly in front of the family, shocking them. Haruka is troubled and investigates the cause, and finds that it seems to be influenced by the fact that her younger brother's male friend is having sex with their mother. After learning that her younger brother is innocent about sex, Haruka decides to instill proper sexual knowledge in him...