Naruto and Kat are the key characters. Naruto, with his orange jumpsuit and his dreams of becoming Hokage, has a whole set of ninja techniques. Kat, who is from a world filled with the supernatural, has powers that are yet to be fully explored in the context of this fanfiction. As the two main characters, they will face challenges together, learn from each other, and their relationship will be at the heart of the story, whether it's a friendship or something more complex as the plot unfolds.
Obviously, Naruto and Kat are the main characters. Naruto, the energetic and determined ninja from the Hidden Leaf Village, brings his combat skills and positive attitude. Kat, from the supernatural world, has her own set of powers and a personality that's likely different from Naruto's. They are the two main characters whose interactions drive the story forward.