It might also be a completely new character created for the fanfiction. This new character could be wearing a mask for a unique reason, like hiding a special power or being part of a secret organization. The fanfiction could then revolve around this new character's journey and how the mask plays a role in it.
It could be Sasuke. He might be wearing a mask for some mysterious reason, like hiding his new powers or a new allegiance. Maybe he's on a secret mission that even Naruto doesn't know about at first.
Sasuke could be a great candidate. He has always been a bit of an enigma, with his brooding nature. He could be hiding a new power or a different side of his personality behind a mask, either self - imposed or as a result of some outside influence. Maybe he's trying to hide his true intentions from Naruto and the others as he pursues his own goals.
It might also be a new character created specifically for the fanfiction. This character could be someone who has infiltrated the Hidden Leaf Village, living behind a mask of false loyalty while having their own secret motives and goals.
Astrid is also a possibility. She's a strong - willed character, but perhaps there's more to her than what we usually see. She could be hiding her softer emotions or insecurities behind a tough - girl mask. For example, she might be secretly worried about her relationship with Hiccup or her place in the tribe.
Kakashi could be another option. He is a highly experienced and intelligent ninja. If he came across the skull mask, he would approach it with caution. He might study it first to understand its origin and power before deciding whether or not to use it. His calm and collected nature would be a great contrast to the potentially wild power of the mask.
It could be a new villain. A character with a cracked mask might be introduced as a powerful adversary. The cracks in the mask could be a sign of their unstable power or a damaged psyche. They could have a vendetta against Naruto and his friends, and the story would be about Naruto trying to stop their evil plans.
Well, it could be about exploring the hidden identity of someone who wears a mask in the Naruto universe. Maybe it's a new character who has a secret agenda, or perhaps it's a known character with a new side to them that is only revealed when the mask is on.
One possible reason could be for protection. Maybe Naruto is hiding his true identity from an enemy who is specifically targeting him. He might be using the mask as a disguise to blend in and gather information without being recognized.
It could be someone who also wants the power of the mask. Maybe a rogue ninja who has been researching the mask for a long time and sees Naruto as an obstacle to obtaining it.
Sasuke could discover Naruto's true identity. They have a deep connection and Sasuke is very perceptive. He might notice small details like Naruto's mannerisms or the way he talks, even when Naruto is behind the mask.