According to publisher Shiravune's description of the game,

Seiran Island, a tropical eden where people are free to act on their desires under a uniquely libertine law. But even here in paradise, there are those who work in the shadows to bring it down…

United, these misfits stand side by side as the secret society NLNS.
As their founder and head honcho, I, Junnosuke Tachibana,
won’t stop until we’ve crushed this crazy law once and for all!

I’ve even found a benefactor in this crusty old rich guy, name unknown…
He’s hooked us up with a secret base and a buttload of cash already.
In return, he wants us to find someone and “protect her at all costs.”
Apparently, she holds the key to our mission’s success…?

In which case, there’s only one thing to do: locate this mystery girl.
And all while keeping the SHO off our scent, too…

Make no mistake! I’ll stop that law in its tracks, just wait and see!