Danzo could also be a possible antagonist. He might have his own plans for the Chunin Exam, perhaps trying to manipulate the results to get certain genin under his control. His shadowy and self - serving nature would create a lot of conflict, especially when Kakashi and Naruto start to suspect his motives.
Naruto could be the main singer. He has a big personality and is always ready to take on new challenges. His lack of singing skills at first could add an element of growth and humor to the story as he tries to improve and surprise everyone with his performance during the Chunin Exam.
Perhaps an old enemy of Naruto's who resurfaces and decides to target his family. This could be someone who was defeated by Naruto long ago but has now grown stronger and wants to cause harm to his loved ones. They might also see Kakashi as a threat in protecting the family.
There's also a chance that a new character could be the main character in the fanfic. Maybe someone who has a special connection to the chunin exam, like a character from a minor clan who has a hidden power and wants to prove himself during the second chunin exam.
Danzo could be a great antagonist. If Kakashi travels back in time, Danzo's underhanded plans, like his control over Root and his desire for power, would still be in motion. He'd likely oppose Kakashi's attempts to change things for the better, especially if it threatened his own influence.
Maybe he realizes the exam is too dangerous or he discovers some unfairness in it. In the original Naruto story, Naruto has faced many difficulties and moral dilemmas during the Chunin Exam. So in the fanfiction, similar situations might push him to quit.
Another plot could revolve around a new type of jutsu that is introduced during the Chunin Exam. For example, a forbidden jutsu that some rogue ninja tries to steal during the exam, and Naruto and Kakashi have to team up to stop it. This would add an element of danger and mystery to the fanfiction.
Perhaps a powerful shinobi from another village who has a special grudge against the Leaf's ANBU. He targets Kakashi and Naruto specifically because of their reputation within the ANBU. He has unique abilities that pose a great challenge to them, like the ability to nullify ninjutsu for short periods.
The main characters would most likely be Naruto, Kakashi, and the other genin participating in the Chunin Exams. Naruto is central to the Naruto series, and his performance in the exams is always a big focus. Kakashi, as his sensei, would play an important role in guiding and protecting him. The other genin like Sasuke, Sakura, and the various opponents from other villages are also likely to be main characters as they are key to the drama and action of the Chunin Exams.
In a 'Naruto Kakashi Chunin Exams' fanfiction, there could be many exciting things. For example, Kakashi might reveal some new jutsus to his students during the exams. Naruto could face unexpected opponents and overcome them in unique ways, showing his growth as a ninja. There might also be new twists in the exam rules, created by the author to add more drama.
Maybe an organization that wants to use her unique abilities. If she has inherited some special power from Kakashi or has her own distinct skills, an evil organization could try to capture her and force her to work for them. They would be the main obstacle she has to face in the story.