I'm not entirely sure as it's a very specific Japanese phrase. 'kami' can mean 'god' or 'upper', 'no' is a possessive particle, 'techigai' might mean 'substitution' or 'exchange', and 'de shindara' could be something like 'if died by' and 'novel' is just 'novel'. But this is a very rough translation.
I'm not sure if it is a popular novel. There are so many novels in Japan that it's hard to say without more research. Just from this title, it doesn't seem like a well - known one to me.
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.
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.
Maybe Jiraiya. Since Jiraiya was Naruto's mentor and taught him a lot of things. He might have some knowledge about summoning kami and pass it on to Naruto.
Many 'kami naruto fanfiction' pieces tend to blend the spiritual elements of Kami with Naruto's more physical and combat - oriented world. They might explore how Kami's existence affects the balance of power in the ninja villages. Also, these fanfictions sometimes create new relationships between Kami and other characters in the Naruto universe, like Kami having a special bond with Kakashi or Sasuke in some stories.
Ino could be a potential member. Since she has a strong connection with mind - related abilities, she might be intrigued by Naruto's new connection with fem Kami and get involved in the harem. Also, Sakura might be part of it. Despite her initial feelings for Sasuke, she could see Naruto in a new light after his encounters with fem Kami and join the group.
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.