In some Naruto Kamui fanfiction, characters like Minato might be popular. He was a very powerful ninja, and imagining how he would interact with Kamui, either through his own knowledge or through his connection to Kakashi, can make for an interesting story. Also, characters from other villages who are intrigued by Kamui's power and try to steal or understand it better can be a part of these fanfictions.
Well, Kamui is the central figure, no doubt. In addition to him, an OC with special powers, like the ability to control elements, is often seen in these fanfics. A female OC who has a complex relationship with Kamui, whether it's friendship or something more, is also popular. And then there's the sidekick - type OC, a humorous and loyal character who is always there to support Kamui and provide some comic relief in the story.
Yes, there is a Ninja Kamui manga. It has gained popularity for its action-packed scenes and interesting character developments. Many fans enjoy collecting and reading it.
Naruto using Kamui could change the power dynamics in the Naruto universe in the fanfiction. His battles would become more unpredictable. For instance, against strong opponents like Madara or Kaguya, Kamui could be used in creative ways. He could use it to send parts of their attacks to another dimension, or quickly dodge attacks and counter - attack from unexpected angles. It also might make his allies view him differently, as this new power is something very different from his normal ninjutsu.
In many fanfictions, Naruto might initially discover Kamui through an encounter with Obito or Kakashi. Maybe during a battle where he witnesses the power of Kamui first - hand, and his inquisitive nature leads him to start exploring how to learn it.
In some fanfictions, Naruto might acquire the ability to use Kamui through a special encounter. Maybe he meets an ancient sage who imparts this power to him, seeing Naruto's potential and his need for an edge in battles against powerful foes.