Who could be the main antagonist in the 'naruto loses his voice' fanfiction?

It could be Kaguya. If Kaguya were to return and use her powerful abilities to drive Naruto mad, perhaps by invading his mind with dark thoughts and memories. She has the power to warp reality and minds, so she could easily make Naruto lose his sanity. And since she has a grudge against the world of ninjas, making Naruto, one of the most powerful ninjas, go insane would be a great way for her to start her reign of terror all over again.

A new and mysterious dark ninja could be the main antagonist. This character might have a special ability to corrupt others. They target Naruto specifically because of his power and influence. By using some form of dark jutsu or psychological manipulation, they make Naruto lose his humanity, turning him into a weapon against the very people he used to protect.

It could be a new, powerful ninja from a hidden village. This ninja has a special ability to manipulate the chakra related to emotions. He sees Naruto as a threat because of his popularity and power, so he uses his ability to make Naruto lose his emotions, hoping to weaken him and his influence.

It could be a rogue ninja from a hidden village that has a grudge against Naruto. This ninja might have a special jutsu that specifically targets Naruto's left eye during a fight, causing him to lose it.

It could be a new and powerful rogue ninja who manages to overpower Naruto and cause him to lose his arm. Maybe this antagonist has some sort of vendetta against Naruto or the Hidden Leaf village.

It could be a new dark wizard who has a vendetta against Harry. This wizard might have created a spell specifically designed to target Harry's emotions, as he knows that Harry's strength often comes from his love and friendship. By taking away his emotions, he hopes to weaken Harry and make him easier to defeat.

It could be a new villain who has the power to manipulate memories. This villain might target Deku specifically because he sees Deku as a threat to his plans. He wants to erase Deku's memory so that he can't interfere with his evil schemes in the hero world.

Voldemort could be the main antagonist. He might have seen the potential in Harry's twin and decided to get rid of the twin to weaken Harry or use the twin for his own dark purposes.

It could be a marine admiral who has developed a new weapon that not only causes physical harm but also memory loss. This admiral might see Luffy as a big threat and decides to use this weapon on him to weaken the Straw Hat crew.

It could be a new, mysterious ninja from a far - off land. This ninja might have a vendetta against Naruto for some reason, like Naruto interfering in their plans before. They could be extremely powerful and use some sort of dark jutsu to target Naruto's eye specifically.