Uta is a world-famous singer or “diva” and the adopted daughter of Red-Haired Shanks. She was also a musician in his crew, until he left her while she was still a child. She is the main antagonist of One Piece Film: Red.
The question that many are asking now: is Uta “canon”?
Well, first of all, let’s try to explain the concept of canon. “Canon” is a term people use when certain events happen in the story that is labeled “official” by the creator and or fans. Say if in the manga (comic version of the anime that came out first) a supporting/secondary character is killed. This is now canon to the story as made by the creator.
Now let’s say the anime changed the events and the character is now in a coma, that is now non-canon and can be considered it’s own canon.
One Piece Film: Red is not canon in terms of the current manga continuity. Even before the movie was released, Shimizu, the producer, already announced that One Piece Film: Red is a separate story.
But even if the film is not canon, Uta is considered canon as she was created by Oda. Many fans realized an important detail: Oda included Uta in Chapter 1055, where you can see her silhouette.
This means that she is canon and her past with Shanks is essential to the overall story. Uta is also Luffy’s childhood friend, which adds more importance to her character.
Recently Oda confirmed that Luffy’s love for singing and music was influenced in part by Uta, further elaborating that the reason why Luffy always wanted a musician in his crew was specifically because of his past together with her.