Well, Naruto is the obvious main character. However, depending on the plot, characters like Kakashi could be involved as well. He could be guiding Naruto in handling his godlike powers. And the villains in the fanfiction could also be main characters in a sense, as they would be the ones creating challenges for Naruto in his new state with the godlike bijuu powers.
Maybe there's a rogue ninja who has developed a new and dangerous jutsu that can counter Naruto's powers. This ninja wants to prove himself as the strongest by defeating Naruto and taking over the bijuu's power. He might be jealous of Naruto's newfound status and the respect he gets from the other ninjas.
Obviously Naruto is one of the main characters as the title implies his role as the master of bijuu. Other characters could include his friends like Sasuke and Sakura. Since it's related to bijuu, the jinchuriki of other bijuu might also be important characters, like Killer Bee who was the host of the Eight - Tails.
It could be about Naruto attaining a god - like form related to the bijuu. Maybe he gains incredible powers that are far beyond normal and the fanfiction explores his adventures and battles in that state.
In some popular 'naruto female bijuu fanfiction', characters like Hinata can often be reimagined as a female jinchuriki. Another common main character is an original female character created specifically for the fanfiction. Sometimes, Sakura is also given the role of a jinchuriki in certain fanfictions.
The bijuu are the main characters as they are the focus of the 'goes to Yuki Academy' part. However, depending on how the story unfolds, there might be some side characters like the academy's janitor who has some secret knowledge about the bijuu and ends up helping them in unexpected ways, but still, the bijuu are the central figures.
Sasuke could also be a main character. His quest for power and his unique abilities might make him interested in the artificial bijuu. He could either be trying to use them for his own goals or be against their existence, depending on the plot of the fanfiction.
There might be original characters created specifically for this fanfiction. These could be characters who are either servants or opponents of the godlike Nara. They could bring new plot elements and conflicts. For instance, a mysterious figure who has a vendetta against the Nara clan for their new - found power could be introduced. This would add more depth and complexity to the story and give the Nara character more opportunities to show their godlike abilities in combat or strategy.
Well, Naruto is the central figure as the title implies. But there could be other important characters too. There might be some new characters introduced specifically for this fanfiction. For instance, an old master blacksmith who teaches Naruto some traditional blacksmithing techniques, even though Naruto has his godlike abilities. And of course, his friends and foes from the original Naruto story may also be part of the story to create interesting interactions.
Well, obviously Naruto and Hana are the main characters. Naruto, with his godlike powers in this fanfiction, is a force to be reckoned with. Hana, on the other hand, brings her own skills and personality to the story, and their interactions form the core of the fanfiction.
It could be Naruto himself. Since he's the main character in the original series, it's likely that in this fanfiction, he might be the one to develop godlike kenjutsu skills.