One possible reason could be to correct some mistakes in the future. Maybe there were some events that led to a really bad outcome, like the destruction of the Hidden Leaf Village, and Kami thought sending Naruto back in time could prevent it. Another reason might be to give Naruto a chance to learn more about his predecessors and gain new powers or knowledge that could help him in his original timeline.
Often, Naruto is sent back to a time when he can prevent a tragic outcome or gain crucial knowledge. It could be to the time before his village was attacked or when a key character made a fateful decision.
Naruto's knowledge from the future could have a huge impact. He might introduce new fighting techniques or ways of thinking that were not present in the past. This could change the balance of power among the ninja villages. Also, his actions could influence the relationships between different clans. For example, if he befriends a clan that was previously isolated, it could lead to new alliances and change the political landscape of the ninja world.
Maybe it's a completely new and unknown kami. A kami created specifically for this fanfiction. This kami could have unique powers and a different view of the ninja world compared to the existing characters in Naruto. It would add a fresh and exciting element to the story.
Maybe it's an existing character from Naruto who has been elevated to Kami status. For example, Tsunade could be turned into a Kami, and Naruto's relationship with her could be a very different dynamic from their previous ninja - leader relationship. Or it could be Kaguya, who was already a very powerful being, and in this fanfiction, she reforms and becomes a Kami and Naruto's wife.
In fanfiction, the 'kami' could be an original deity created by the author. This new 'kami' could have its own motives and reasons for giving a gift to Naruto. Maybe it's a kami that has been observing Naruto's journey and decides to interfere to help him achieve a greater purpose. It could be a kami associated with nature, like a kami of the wind or the fire, and the gift could be related to that element.
Yes, there might be such fanfictions. One possible plotline could be that Kami has been corrupted in some way and Naruto, in his sense of justice, has to take extreme measures. Maybe Kami starts to harm the village or its people, and Naruto, as the protector, has no other choice but to fight and end Kami's existence. Another could be that Naruto is tricked into believing Kami is a threat when in fact it's a misunderstanding created by an enemy.
Perhaps it could be a female version of an existing kami from Naruto lore. For instance, a female counterpart of the Sage of Six Paths. She would have vast knowledge and power, and her training of Naruto would be a way to pass on that ancient wisdom and strength.
It could be about Naruto obtaining kami - like powers. Maybe he discovers he has a connection to the kami and has to learn how to control these new powers to save the Hidden Leaf Village from a great threat. Or perhaps he is chosen by the kami to be a sort of bridge between the human and divine worlds in the Naruto universe.
A possible plotline could be that Naruto is chosen by Kami for some greater purpose related to the balance of the world. As a result, they get married. Their union then brings about a new era of peace and prosperity as Naruto uses Kami's power to end all wars. Another plotline might be that Kami falls in love with Naruto's pure heart and determination. She decides to marry him, but they first have to convince the shinobi world that their union is for the good of all.
It could be a doujutsu that allows him to see the future in fragments. So he can get glimpses of his opponents' next moves or potential threats in the near future.