Another possible gain is in terms of wisdom and a deeper understanding of the ninja world. Kami, being a more enlightened being in the fanfiction context, could impart knowledge about the history and hidden secrets of the ninja world. This could help Naruto make better strategic decisions and also give him a new perspective on his role as a ninja and a potential leader.
He might gain enhanced spiritual powers. Kami could teach Naruto to better sense and interact with spiritual energy, which could give him an edge in battles against opponents with spiritual - based attacks.
Naruto could learn new jutsu related to divine or celestial elements. Since Kami is often associated with a higher power in many mythologies, Naruto might be able to harness powers like celestial fire or divine wind through this training. This would not only expand his offensive capabilities but also make his attacks more unique and difficult to counter.
He might gain enhanced chakra control. Since Kami is a powerful entity, Naruto could learn to manipulate his chakra in ways he hadn't before, like creating more complex jutsus with less effort.
He could gain better stealth skills. Hidan is quite good at sneaking around and Naruto might pick up on that. So he could move more quietly and be better at surprise attacks.
In fanfiction, Naruto could gain enhanced sensory abilities. Since toads are known for their connection to nature, Naruto might be able to sense things from a greater distance, like the movements of enemies or the flow of chakra in the environment. This would give him an edge in battles.
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.
He could potentially gain an enhanced understanding of wood - style techniques. Since Hashirama was a master of it, Naruto might learn how to create more complex and powerful wood constructs, like huge forests for both offense and defense.
He could gain the ability to sense death. Maybe he can tell when someone is close to dying or if there's a dangerous situation that could lead to death. It would be like a sixth sense.
In the 'naruto trained by fem kami fanfiction', perhaps the fem kami sees Naruto's potential and decides to train him secretly. She might introduce him to new realms of chakra control and spiritual awareness. This training could involve Naruto having to face otherworldly challenges that are far beyond what he's used to in the Hidden Leaf Village. It could also lead to Naruto having a different perspective on the ninja world as a whole, since he's being trained by a being from a different plane of existence.
Naruto could gain the ability to use different forms of his Nine - Tails chakra more effectively. Since Killer Bee has great knowledge about Jinchuriki powers, he could teach Naruto how to access and use his chakra in ways he hadn't thought of before. Also, Naruto might learn new physical combat techniques from Bee, like improved hand - to - hand combat skills or new ways to use his kunai and shuriken.
He might gain better chakra control. Kakashi could teach Naruto how to precisely manage his chakra, allowing him to perform jutsus more efficiently and for longer periods. For example, Naruto could use his Shadow Clone Jutsu without exhausting his chakra so quickly.
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.