NUKITASHI THE ANIMATION

The tropical, isolated island of Seiran.
Junnosuke Tachibana, who was born on this island, returns to his home island with his younger sister, Asane Tachibana, after the death of their parents.
However, Seiran Island has become a place of madness.
In an attempt to halt the declining population, the island enacted the Pervert Law that not only permits but actively encourages sexual activity anywhere on the island.
Refusing to participate in these "reproductive activities" is a punishable offense.
A proud virgin and an obsessive defender of female purity, Junnosuke, finds the law deeply questionable.
Determined to protect both his own and his beloved sister's innocence, he establishes the anti-mating resistance group known as the NLNS (No Love No Sex), and begins moving to destroy the Pervert Law!
"I'm going to crush this Pervert Law!"