My name is Chifuyu, and I have an older twin sister named Chinatsu who's good at both studies and sports.
My older sis has everything that I've always wanted. For example... Haru-kun, the junior whom I've always loved, among other things.
One day, I ended up helping Haru study, substituting for my sister. It started with an incident where he unexpectedly got an erection, that I learned that he and my sister haven't had sex yet.

So, they haven't done it yet...
In that case, then I will...

I did things like suck his dick while making an indecent face and lick his nipples while riding him in the cowgirl position.

Just one thing. I can at least have his first time. Right, sis?

Daikon Arimura-sensei, a new writer of "Reverse NTR" stories, presents a sex story of a girl squeezing the virginity out of her sister's boyfriend☆

(Source: DLsite)