Another possibility is a new character. Maybe a young, unknown ninja who dies unjustly and is then reborn as a sennin. This character would have to learn to adapt to their new powers while also dealing with the politics and challenges of the Naruto world. They could bring a fresh perspective to the story, not being bound by the pre - existing relationships and grudges of the well - known characters.
It could be Naruto himself. Imagine if he was reborn as a sennin. He would have all his previous experiences and then the added power and wisdom of a sennin, which would make for an extremely powerful and interesting character to follow.
It could be a powerful dark ninja who has discovered a way to tap into an ancient and evil power source. This ninja wants to use this power to rule the ninja world and sees Rikudou Sennin's rebirth as a threat to his plans.
The main character is Naruto as he is the heir of the Rikudo Sennin. However, other characters are likely to be involved too. Jiraiya could be a key figure in this fanfiction, considering his connection to Naruto and his knowledge of the past. Additionally, the antagonists in the Naruto world might also be main characters in a sense, as they would oppose Naruto's rise as the heir, either out of jealousy or a desire for power themselves.
One idea could be the protagonist exploring new jutsu combinations after being reborn as a sennin. They might use their newfound knowledge and power to change the course of events in the Naruto universe.
One interesting plot could be that Rikudou Sennin is reborn into a time when the ninja world is on the verge of a new, unknown threat. He has to quickly regain his powers and knowledge to guide the new generation of ninjas, like Naruto and his friends, to face this threat. Maybe he has lost some of his memories in the rebirth process, adding an element of mystery and self - discovery to the story.
One of the potential allies for Naruto in his Dead Edo Tensei state could be Gaara. They have a mutual respect for each other, and Gaara would understand the importance of Naruto's role even in this undead form. Tsunade might also be an ally. As the Hokage, she would see the value in Naruto's continued existence and would use her medical and leadership skills to support him. Shikamaru, with his strategic mind, could be an important ally too. He could help plan how to best utilize Naruto's Edo Tensei abilities and deal with any threats that come their way.
Jiraiya is also frequently a main character in these fanfics. He's a well - known sennin in the Naruto world. Fanfic writers might explore his past more deeply or create new adventures for him. Another common character is Tsunade. Her relationship with the other sennin and her unique abilities make her an interesting addition to many fanfics.
Another main character could be Kakashi. As Naruto's teacher, he might be involved in the story when the Kitsune Sennin starts to train Naruto. He could be skeptical at first but then come to understand the importance of the Kitsune Sennin's teachings. Also, his own experiences and knowledge could interact with what the Kitsune Sennin brings to the table, adding more depth to the story.
He could revive Minato. Minato was a very powerful ninja, and his return could help Naruto in terms of combat skills and strategic thinking. Also, Minato could pass on some unique jutsus or knowledge that he didn't have a chance to before.
Obviously, Naruto would be one of the main characters since it's in the title. He's the one who has mastered Edo Tensei. There might also be characters like Sasuke. Sasuke could be either an ally or an antagonist depending on how the story goes. Maybe he's jealous of Naruto's new power or he wants to use it for his own purposes.
Sasuke is often paired with the Kitsune Sennin in some fanfictions. Since Sasuke is also a powerful ninja, the Kitsune Sennin might see potential in him and try to guide him as well, which could lead to an interesting dynamic between Sasuke and Naruto. Another character is Kakashi. Kakashi's Sharingan and his vast knowledge could interact in interesting ways with the Kitsune Sennin's powers and wisdom. It could create scenarios where they exchange knowledge or team up to train Naruto.