The story of Ran, the older sister of the twin sisters in the Shiraishi family. Ran is proactive and full of initiative. To do lewd things with her beloved brother, she asks him to teach her lessons. Her brother knows he shouldn't fall for it but still gets drawn in by Ran... And then this gets found out by her younger sister Non, leading to the sequel 'The Shiraishi Family Twin Sisters: Younger Sister Non-chan'
