It could be an unknown elder ninja. This elder has seen the rise of fanfiction and its potential threats to the real ninja world. He has unique powers and techniques that are specifically designed to deal with such non - traditional threats. So, he takes Naruto under his wing and trains him to kill the fanfiction.
Maybe Kakashi could be the one. He's always been Naruto's mentor in many ways. He has the knowledge and skills to train Naruto for such an unusual task. He could use his Sharingan to analyze the fanfiction and teach Naruto how to spot the dangerous elements within it.
Another option could be Itachi. Although Itachi is from a different village and has his own complex situation, in a fanfiction scenario, he could secretly train Naruto. Itachi has extremely powerful jutsus and a deep understanding of the Sharingan. Training under him would give Naruto a very different perspective on power and combat, not to mention some insights into the Uchiha clan.
Well, Kurama might train Naruto by teaching him how to better control and access chakra. Since Kurama has a vast amount of chakra, it could show Naruto unique ways to harness and use it. For example, it could guide Naruto in creating more powerful and complex jutsu by using their combined chakra in a more efficient way.
Well, perhaps Naruto is forced into a strange situation where he has to combat the ideas and stories in fanfiction that are causing some sort of chaos in the ninja world. Maybe some evil force is using fanfiction to distort the real story of the ninja world and Naruto is the only one who can stop it by 'killing' these false narratives.
Well, it could be about Naruto being forced into a dark situation where he has to train for killing. Maybe he's been misled or there's a great threat that makes him think this is the only way. For example, he might be tricked by an enemy who disguises as a friend and convinces him that the only way to protect the village is to become a killer.
It could be a rogue ninja from a forgotten clan. This ninja might have a vendetta against Naruto's village and has powers that are difficult to counter. So, Naruto has to train to kill him to protect everyone.
Another aspect of the training could be mental discipline. Hayate may introduce Naruto to meditation - like techniques to help him focus his chakra more effectively. He'd also likely teach Naruto how to keep a calm head in the heat of battle, sharing his own experiences to illustrate the importance of mental fortitude.
Naruto would gain better combat awareness. Kurama's experience in battles can be passed on to Naruto. He'll be able to read his opponents better, know when to attack and when to defend. This will make him a more formidable opponent in combat situations.
Naruto may become more calm and composed. Itachi's presence and training methods would likely instill a sense of discipline in Naruto. He'd probably be less impulsive in battles and think more before acting.
No. Fanfiction is a form of creative expression. Naruto fans write fanfiction to explore different ideas and stories within the Naruto world. Just because someone doesn't like it doesn't mean it should be 'killed'.
Well, in fanfiction, Naruto being trained in different ways can bring more variety to his character. He can be trained in unique fighting styles or gain knowledge that was not available in the original story. This can make him more versatile in different storylines. Also, it can attract more readers who are looking for new and exciting takes on Naruto's development.