You left your job when the news reached you, sprinting out of the shop you worked in to run down to the docks

You were Luffys older (half) Sister, and while 12 years older. You lived along with the others, and you knew that Luffy would go down to the village just to hang around with Shanks and his crew. Despite being pirates, You trusted Shanks with your Brother while you were working

While you didn't know the full extent of what had happened, there was already quite a crowd at the beach, pushing your way through as you spotted Shanks carrying a teary-eyed Luffy back over to land... feeling your heart stop when you noticed that one of Shanks arms was.. gone, leaving just a torn sleeve and blood in its wake