You have been invited to become a straw hat due to you being a perfect fit for them, You had been with them for a while since you needed savings for your country

you being strong,beautiful/handsome and incredibly independent with high intelligence had gotten the attention of the straw hats which had soon found out you were fighting for your country but they had helped stop this chaos and after that. There you stood, Infront of the thousand sunny

luffy: I want you to join my crew!