Well, Naruto is a given. Then there could be other minor gods or spirits in Kami's realm that Naruto meets. Maybe there's a guardian spirit of the ninja world that only appears when someone tries to reach Kami. Also, characters like Kakashi could be involved. He might have some knowledge about Kami that he imparts to Naruto before the journey, or he could even end up joining Naruto on his adventure to Kami.
The main character is Naruto. In the past, he will surely encounter his parents. Minato and Kushina would be important characters in this fanfic. Also, Jiraiya, his mentor, would be a key figure. Since Naruto is going to the past, he might seek Jiraiya's guidance even more. And characters like Orochimaru would also be part of the story as Naruto may try to stop Orochimaru's evil plans earlier.
Obviously, Naruto and Orochimaru are the main characters. Naruto is the protagonist who is going to Orochimaru, and Orochimaru is the one Naruto is going to see.
Obviously, Naruto would be one of the main characters as the title implies he is the one being saved. And the Kami, which is the one doing the saving, would also be a main character. It could be an existing Kami from the Naruto series, like the Sage of Six Paths who could be considered a Kami - like figure, or it could be an entirely new creation for the fanfiction.
Obviously, Koyuki herself would be a main character to interact with Naruto. She might show him around her place, introduce him to her people. Also, any of her loyal guards or advisors could interact with Naruto. They could be initially suspicious of him but then grow to trust him as they see his good intentions.
Sasuke could definitely be one. He might be conflicted about Naruto's banishment, either thinking Naruto deserved it at first and then changing his mind, or trying to find a way to bring Naruto back. Kakashi could also be in it. He might be one of the few in the village who believe in Naruto's innocence and try to secretly help him.
Well, in the 'naruto trains and returns to konoha fanfic', Naruto is the central figure. For his training, he could meet some new characters who are experts in certain ninja arts. But in Konoha, all his old comrades will be there. Shikamaru, who is known for his intelligence, might be involved in planning something related to Naruto's return. Ino could be there too, perhaps using her mind - related jutsus to help in some way. And of course, the old sages or elders of Konoha would also be present to assess Naruto's growth and the impact of his return on the village.
Well, it could be about Naruto going on a spiritual journey to meet Kami. Maybe he's seeking some sort of power or knowledge that only Kami can provide. He might face various challenges along the way, like powerful spirits or difficult terrains.
Obviously, the young justice members themselves will be there. And then, of course, Batman is very likely to show up. He is Gotham's main protector after all.
Sasuke could be involved. He might be initially skeptical or jealous of Naruto's new blessing but later come to understand its importance. Kakashi could also play a role, perhaps guiding Naruto on how to control and utilize this new power.
Sasuke would be a likely character to appear. Since he and Naruto have a deep connection, Sasuke might cross paths with Naruto during his wanderings, either as an ally or an antagonist depending on the plot.