There could be a powerful organization that has been secretly manipulating events in the ninja world. They might have been behind some tragedies that Naruto wants to avenge. This organization could have members with unique and dangerous abilities, making them formidable antagonists for the godlike Naruto.
It could be a new group of rogue shinobi who have been causing chaos in the ninja world while Naruto was away. They might have targeted Naruto's friends or family, which is why he's back for revenge.
Maybe the hidden organizations within Konoha that work in the shadows. They could have been involved in some plot against Naruto that led to his decision for revenge. They would be the ones trying to stop Naruto from exposing their secrets and exacting his revenge on the village as a whole.
Well, perhaps Naruto comes back with incredible powers. He might be seeking revenge on those who wronged his village or his friends. Maybe he was betrayed in the past and now he's back to make things right and punish the traitors.
Perhaps there are dark forces from another dimension. These forces might be attracted to Naruto's power and want to either steal it or destroy him to prevent him from using it against them. They could be powerful demons or sorcerers with their own motives.
Another possibility is that the main antagonists could be the leaders of the other ninja villages. They might view Naruto's godlike and rogue status as a danger to the balance of power among the villages. So, they could form an alliance against Naruto, leading to a lot of political intrigue and conflict in the story.
It could be his own family members who abandoned him. They might come back as antagonists, trying to stop Naruto from reaching his full potential or causing trouble for him out of envy or regret. Maybe they have joined a dark force and are now working against him.
In this fanfiction, the main antagonists might be a group of dark chakra - users. They are jealous of Naruto's godlike powers and want to take over the empire for their own evil purposes. They could be using dark magic to corrupt some of the people in the empire, turning them against Naruto. There might also be some power - hungry politicians within the empire who are not satisfied with Naruto's leadership and want to seize power for themselves. They would plot behind the scenes to bring down Naruto and take over the reins of the empire.
Maybe it could be other ninja clans who are jealous of Naruto's newfound sword bloodline. They might see it as a threat to their own power and status in the ninja world.
Well, in this fanfiction, the Akatsuki could be the main antagonists. They would view Naruto's godlike powers as a major threat to their goals. Since Naruto has been trained by Shendu, his abilities would be unpredictable and extremely powerful. They might band together to try and take Naruto down. Additionally, there could be some ancient demons or spirits that are awakened by Naruto's new powers and they see him as an intruder in their realm, so they become antagonists as well. They would use their own dark magic and powers to oppose Naruto.
The village elders could be the main antagonists. They might see Naruto's godlike powers as a threat to their traditional way of ruling the village and decide to get rid of him. Another option could be a secret organization within the village that wants to use Naruto's power for their own evil purposes and when he refuses, they turn on him.
One possible main antagonist could be a powerful being that controls the different dimensions and sees Naruto's hopping as a threat to his order. Another could be an evil version of Naruto from another dimension who wants to stop our Naruto from spreading his 'good' influence. Maybe a group of rogue dimension - travelers who are causing chaos in different dimensions and Naruto has to stop them.