As we all know now, Yamato has met Ace “Burning Fists” at one point before the Straw Hats arrive in Wano. This meeting made it possible to better understand who is Yamatoand its relation to Ace. There was a lot of hate towards Yamato since its inception, but we believe that this hatred is quite misplaced.
The identifying alias of Yamato (Oden Kozuki) is just that, an alias given to herself by herself because she has a purpose she wants to fulfill.
As shown in the image below, Yamato led the only active effort to resist Kaido. for years because, to his knowledge, the Akazaya Nines were all dead. She has ALWAYS been an ally to the crew – years before we even met them.
The encounter with Ace sparked his active rebellion against Kaido. Ace told him to stop leaving Kaido chain his heart.
And Luffy physically freed her.
Here we learn the reason for his self-stylization. The alias of Yamato, Odenwas the symbol of the freedom.
Yamato’s desire for freedom was so great that as a child, she unlocked her Innate Conqueror’s Haki.
And to those who claim she will never be allowed on the ship because she knows where Laugh Tale is or what One Piece is… Well, Momonosuke confirmed that someone (presumed to be Oden) deleted all important details of the trip he was on to prevent the wrong hands from learning anything before Wano opens its borders.
In sum, Ace told Yamato to find Luffy if he never came back. This implies thatAce made a promise through time for Yamato to join the Straw Hat crew under the orders of Luffy – a promise that Luffy would never fail to hold on for love’s sakeAce.