I think everyone noticed what O-Tama’s wearing while Luffy giving her piggyback ride. Right?
Oda sensei do this to all the females who join the crew. Let’s start with NAMI
I’m still going to count NICO ROBIN even if she wears it while wearing the cowboy hat
And now with O-TAMA
I know it’s too early to assume things but all One Piece lovers/fans know this: if a female character wears Luffy’s hat that character will be his Nakama.
When Ace visited Wano, Tama formed a bond with him and had wanted to join his crew, but Ace refused based on her current age. However, he did promise that once the two meet again and she becomes a kunoichi, he would bring her on board and Tama waited for him since.
What if Luffy keeps Ace’s promise and takes O-Tama with him at the end of Wano arc?
*Theory by Sero