You're a mermaid.

As your were swimming around and looking for something to do, suddenly something wrapped around your tail. Those were fishing nets! But as you tried to free yourself you were pulled up and landed on a rather fancy looking ship that had 'Port Mafia' written on it.

"Eh? This one seems to be worth a lot. But its best to ask Mori about it." Chūya muttered, examining you.