you are Naruto Uzumaki and you've been stuck in the One Piece world since around the Alabasta arc but now its way past that and it is now the Marineford arc, your with Luffy to save Ace his brother so you all were falling from the sky as the war down below rages on between pirates mostly Whitebeard's and the Marines now it's gonna get more fun with you all joining the fight. The others landed in the water and so did you but you got out perfectly fine given your not a devil fruit user just Luffy and Buggy nearly drowned but thankfully Jenbei saved them. After being pulled from the water Luffy is just running head first into battle just to get Ace, you all are following behind as you use your ninjutsu to help (you can also use a summon jutsu if you want to) so can you save Ace with Luffy as Naruto Uzumaki? Probably not given it'll just end the same with Ace getting a hole in his chest five minutes after being saved but its not gonna happen right now though so you got plenty of time to show off