Kakashi could be another important character. As a mentor figure, he might be guiding the younger generation through the difficult times after Naruto's death, using his experience and wisdom to keep the village stable.
Obviously, Naruto would be one of the main characters. His determination and never - give - up attitude would be very useful in a zombie - filled high school. Sakura could also be a main character, using her medical ninjutsu to try and find a cure for the zombie virus. And Sasuke, with his powerful combat skills, would be great for fighting off the zombies.
Obviously Naruto could be one of the main characters. He would bring his unique abilities and his never - give - up attitude. Another could be Rick from The Walking Dead. His leadership skills combined with Naruto's power would make for an interesting dynamic. They could learn from each other and lead the survivors in different ways.
Naruto is surely a main character. Additionally, there might be some original characters created specifically for this fanfiction. For example, there could be a powerful spirit or a guide in the world of the dead who helps Naruto understand his new powers. And characters like Kakashi could also be involved, perhaps providing advice or assistance to Naruto as he deals with the implications of being the king of the dead.
It's hard to say for sure as it's fanfiction, but it could feature Naruto himself. He might be on a journey to understand the secrets of the book of the dead. Sasuke could also be involved as he often gets involved in Naruto's important quests. Maybe even Kakashi could be there, guiding the younger ones with his wisdom about the strange new elements introduced by the book of the dead.
Maybe it's his father, Minato. Minato has a lot of things to tell Naruto, like more about the Uzumaki clan and how to better use the power of the Nine - Tails. And as his father, their connection is very strong, so it's quite possible that he is among the first dead Naruto talks to.
Kakashi could also play a role. He has always been a mentor to Naruto and his sense of duty and loyalty to his student might drive him to search for Naruto when he hears that he's been left for dead. He has the skills and knowledge to find and save Naruto in a difficult situation.
The Akatsuki could also be the main antagonists. They might see the power of raising the dead as a way to achieve their goals. For example, Pain could use the raised dead to spread fear and chaos, or to try and find a way to resurrect Nagato. And they would definitely be a formidable force against Naruto if they were after this power.
Obviously Naruto would be one of the main characters. Depending on the plot, Sasuke could also be involved, either as a helper or an obstacle. Sakura might also play a role, perhaps as a healer trying to save Naruto. There could also be new characters created specifically for this fanfiction, like a dark figure who is responsible for Naruto's 'dead man walking' situation.
Obviously Naruto would be one of the main characters as it's in the title that he's 'broken'. And since Akatsuki is dead, they might still have an impact on the story through flashbacks or the consequences of their actions. Other characters like Sasuke could also be main characters as he's often closely related to Naruto's story.
It varies from one fanfiction to another. Some fanfictions might depict Naruto as dead to introduce a new set of challenges for the remaining characters. For example, if Naruto dies, Konoha might be left vulnerable, and characters like Sasuke or Sakura would have to step up in different ways. But there are also plenty of fanfictions where Naruto remains alive and continues his journey, perhaps facing new and even more dangerous threats than in the original series.