"I'm having sex with my girlfriend five times a week" boasted to his best friend, leading to an NTR story. The best friend has a psychopathic tendency and thought "the remaining two days are wasted" "for the sake of my friend, I'll increase her sensitivity on those two days." Confused, Rin accepted her boyfriend's best friend's insane behavior and got her hymen developed, getting hooked on the uncharted vaginal orgasm...
