Madara Uchiha could also be a likely cause. If he somehow managed to return or had a long - planned scheme that involved breaking Naruto's sanity. He was a very powerful and devious foe who could use his knowledge of the ninja world and its powers to target Naruto's mental stability.
You need to focus on showing his gradual descent into madness through his thoughts, actions, and interactions. Build up the tension and show the triggers that push him over the edge.
Yes, it is. As a Jujutsu Kaisen fan, the 'JJK 0 Light Novel' gives you extra content related to the story. You can learn more about the characters and their relationships, which is always exciting.
Another is the discovery of a dark secret about his family or the village. Maybe he finds out that the village leaders had some malicious intentions towards his family all along. This realization could be too much for him to handle and make him lose his sanity.
Iruka would be a likely candidate. He was Naruto's first teacher and has always cared about him. He would probably notice the signs early on and try his best to bring Naruto back from the brink of insanity. He might use his kind words and the bond they share to reach Naruto.
It depends on your perspective. To some extent, Pecola shows signs of mental instability at the end, but it's also a reflection of the harsh circumstances she's been through and the lack of support around her.
No, Betty isn't insane. She's often shown as a kind, friendly, and sensible person in the comic series. Her actions and behaviors are typical of a normal character.
The Akatsuki as a whole could be the opponents. Imagine Naruto facing multiple Akatsuki members at once in a fight. The combined threat of their different powers and their goals of capturing the tailed beasts could be overwhelming for Naruto. They might use underhanded tactics, like threatening to kill captives or using mind - control techniques on Naruto's friends. All of these things could make Naruto go insane as he battles against them, trying to protect what he loves.
One game is 'Alice: Madness Returns'. It has a really insane story set in a dark and twisted Wonderland. Alice is on a journey through this nightmarish version of the familiar place, dealing with her own trauma and facing off against all kinds of grotesque enemies.