Who could be the main antagonist in a 'naruto retired hokage fanfic'?

It could be a rogue ninja from another village who has a vendetta against Konoha. Maybe he blames the Godaime Hokage for something that happened in the past, like the death of his family during a Konoha - related mission. So, he decides to target the village and the Godaime Hokage in particular.

Perhaps the main antagonist is a spirit or a curse that has been awakened. This curse could be slowly influencing the villagers to turn against Naruto. It could be something that was sealed away long ago and now has broken free due to some mistake or interference. The antagonist could also be a mastermind from another hidden village who is using spies and psychological warfare to undermine Naruto's rule as the Sixth Hokage.

It could be some of the old enemies who were thought to be defeated but managed to come back. For example, Orochimaru's former followers who still hold a grudge against Naruto and Konoha. They might see Naruto's retirement as an opportunity to strike.

One possible plot could be Naruto dealing with the boredom of retirement. He might try to find new hobbies like gardening in Konoha. Maybe he starts teaching some young ninja in an unofficial way, passing on his unique skills and experiences.

It could be a rogue ninja who was once a part of the Akatsuki but managed to escape before their downfall. He's been biding his time, growing stronger, and now he wants to take revenge on Naruto and the Hidden Leaf for what happened to the Akatsuki.

A group of rogue ninjas from other clans who oppose the idea of the Hidden Leaf Village. They see the Shodai Hokage's leadership as a threat to their own power and freedom. They might team up and use underhanded tactics like assassinations, sabotage of the village's resources, and spreading false rumors to try and undermine the Shodai Hokage's authority. They could also form alliances with other enemies of the village, making them a formidable and complex antagonist group.

It could be someone who wants to expose Naruto's secret. Maybe a rogue ninja who wants to use this information to create chaos in the village by making the villagers doubt Naruto's intentions.

It could be a rogue ninja who was once a part of Konoha but was banished for unethical experiments. Now, with a thirst for revenge against Naruto and the village, he returns as a powerful and unpredictable foe.

The fanfiction could be about Naruto's struggle to adjust to a normal life after being Hokage. He might feel a bit lost without the constant stream of paperwork and decision - making. So, he starts to explore his hobbies, like fishing. Meanwhile, he still has to deal with some remnants of old enemies who are trying to take advantage of his retirement, and he has to use his skills and influence in a different way to protect Konoha.

Shikamaru is another possibility. He is known for his strategic mind. As Hokage, he could use his intelligence to make wise decisions for the village. He may not have the brute strength of Naruto or Sasuke, but his ability to plan and analyze situations would be invaluable in leading Konoha.