Using the erotic game by Softhouse-seal Grandee.

In the future, mankind is on the brink of extinction as a result of a drastic loss of the birth rate of males. To counter the declining overall birth rate, the continent features a whole new law as well as the Free Sex Licence. This Licence might be shown to any woman, anytime, anywhere, knowning that woman is legally certain to have relations with its bearer.

Recognized, Takumi receives the type of Free Sex Licence and his awesome life changes drastically. He has sex with Sara, a genius who's also interested in learning sex, along with Misaki, elder sister of his childhood friend Rin. Rin, who's secretly deeply in love with Takumi, is very agitated by these occurrences. However, when Takumi inadvertently displays the licence inside the classroom, Rin's first time is performed in public...