Who could be the main antagonist in 'naruto is not a jinchuuriki fanfiction'?

It could be a rogue ninja who has a vendetta against Konoha for some past wrong. Maybe he was once a Konoha ninja but was wrongly exiled and now wants revenge. Without Naruto having the jinchuuriki power, this antagonist would pose a different kind of threat as Naruto would have to rely on his other skills to face him.

The Jinchuuriki's mentors or those who protect them could also be main characters. For instance, Kakashi could be a main character in a fanfiction where he is tasked with training a new Jinchuuriki. His experience and wisdom would play a crucial role in the Jinchuuriki's development, and his interactions with the other characters in the village would add depth to the story.

It could be an original character created by the fanfiction author. This would give the author a lot of creative freedom to shape the character's backstory, personality, and abilities in relation to being the jinchuuriki of three.

The other Jinchuurikis could be potential allies. They understand the struggles and the power that comes with having a tailed beast inside them. For example, Killer Bee, who has a good relationship with his tailed beast, could share his insights on how to better co - exist with Shukaku. Tsunade might also be an ally, as she is a powerful Hokage who could offer protection and resources to the Jinchuuriki.

It could be Orochimaru. He has always been interested in power and the secrets of the tailed beasts. So, he might see Naruto and the Jinchuuriki family as a source of great power to experiment on or steal from.

It could be someone from the Naruto universe who doesn't like Naruto's newfound fascination with Aku. For example, Danzo might see Naruto's interest in Aku as a threat to the stability of the village and try to stop Naruto from further exploring Aku - related things. So, Danzo could be the main antagonist in this case.

Maybe a new character could be introduced as the main antagonist. This character could be from a hidden village that has been secretly observing Naruto's growth. They realize his potential as a weapon and plan to steal his power or use him to start a war against other villages.

Krampus himself could be the main antagonist. Since he is a figure known for punishing the naughty, his actions in the Naruto world might be seen as unjust. He could be going after ninjas without really understanding their motives, causing a lot of trouble for the main characters.

It could be a rogue ninja who also has somehow acquired bankai - like powers. This antagonist might be jealous of Naruto's newfound abilities and wants to prove that he is the stronger one. So he starts causing chaos in the ninja world, challenging Naruto at every turn.

It could be a rogue ninja who wants to disrupt Naruto's business to gain power. Maybe he's jealous of Naruto's success and popularity in the business world. He could try to steal Naruto's business secrets or sabotage his operations.