Who are some interesting characters that could train Naruto in fanfiction?

A character from another village, like Gaara's father, could be an interesting trainer in fanfiction. He might have unique sand - based techniques and a different view on ninja training. Or perhaps an ancient sage from a hidden land that Naruto discovers during one of his adventures. This sage could have knowledge of a long - forgotten form of ninjutsu that Naruto could learn, expanding his abilities and giving a fresh take on his character development.

In some fanfictions, an older and wiser Sasuke could train Naruto. This would be a great reversal of their earlier relationship. Sasuke, having traveled and gained more knowledge, could share with Naruto some unique Uchiha techniques or a new way of thinking about combat and chakra. Itachi could also be a character to train Naruto in fanfiction. He could teach Naruto about the deeper aspects of the Sharingan and how to counter certain Uchiha - based threats.

Kakashi could be an interesting character to further train Naruto. He already had a role in Naruto's early training, but in fanfiction, he could teach Naruto more advanced Sharingan - related techniques, even if Naruto doesn't have the Sharingan. Another could be Jiraiya's spirit. Even though he's dead, his spirit could come back to offer more sage mode training or teach Naruto some secret jutsu he never got to before.