Well, a great plot might be that Naruto is framed as an assassination specialist by an enemy. So he has to clear his name while also dealing with the real assassins who are causing chaos. Maybe he teams up with some of his old foes-turned -allies, like Gaara, to figure out who's behind it all. They could travel to different hidden villages to gather clues and in the process, Naruto could learn new skills related to stealth and assassination, not to use them for evil, but to stop the real villains.
One plot idea could be Naruto being secretly trained as an assassination specialist by an unknown shinobi from a different village. This could lead to him having a double life, trying to balance his normal ninja duties in Konoha with his secret assassination missions. Another idea is that Naruto discovers a hidden group within Konoha that specializes in assassinations and has to decide whether to join them or expose them.
Perhaps Naruto becomes an assassination specialist after losing someone dear to him in a brutal way. He decides to use his skills to target the criminal underworld that caused the harm. He could start off on his own, but as his actions gain attention, some of his friends, like Shikamaru, might suspect what he's up to. Shikamaru could then either try to stop him or help him depending on the situation. Naruto would have to operate in the shadows, using his Uzumaki heritage and new -found stealth skills to take down his targets one by one.
One idea could be a young trainer who wants to become a type specialist. They start with a single - type Pokémon, like a Fire - type Charmander. As they journey, they encounter challenges specific to Fire - types, like finding places where their Pokémon can train in high - heat environments. Another plot could revolve around a type specialist who has lost their connection to their main type Pokémon due to some emotional trauma. They then have to go on a journey to rediscover that bond. And perhaps a story where a type specialist is challenged by an unknown trainer who seems to have a deep understanding of their type's weaknesses, forcing them to innovate their battle strategies.
One idea could be that the students are kidnapped by an unknown organization that wants to use their unique skills learned from Koro - sensei for some devious plan. The students then have to work together to escape while also trying to figure out the motives of their captors.
Maybe some of the students from the Assassination Classroom end up in the Naruto world. They would be in for a shock with all the chakra and ninjutsu. They could learn from the ninja and apply their own assassination skills in a new context, like trying to 'assassinate' a powerful ninja for training purposes.
One idea could be an OC who has a unique ability related to stealth. For example, they can blend into the shadows like a chameleon. This OC could use this ability to get closer to Koro - sensei without being detected, adding a new dynamic to the assassination attempts. Another plot could involve an OC who is a transfer student from a different school with a completely different teaching style. They struggle to adapt to the chaos of Class 3 - E at first but eventually find their place and contribute to the assassination plans in their own way. Maybe an OC who is a master of disguise and uses it to trick Koro - sensei into various situations where they can try to attack him.
A plot could revolve around Itona getting into some trouble outside of school, perhaps with some people who are after his powers. Karma finds out and decides to help him out of his own sense of justice and also because he has come to care about Itona. They go on a sort of adventure where they have to hide from these pursuers and at the same time figure out how to permanently get rid of the threat. Along the way, they have deep conversations about their pasts, what they want in life, and this strengthens their bond.
One possible mentor could be Zabuza. Although he was an enemy at first, in a fanfiction scenario, he could have survived and seen potential in Naruto. Zabuza was a master of assassination techniques, and he could pass on his skills, like silent killing and the use of the Executioner's Blade in a more covert way. Also, Orochimaru might be considered in a very dark fanfiction. He has vast knowledge of jutsu and poisons that could be used in assassinations, but of course, this would be a very dangerous path for Naruto to take.
A plot could revolve around a time - travel aspect. A student accidentally travels back in time to before Koro - sensei was experimented on and tries to change the course of events. This would involve a lot of moral dilemmas as they might be changing the future for better or worse.
A really interesting plot could be where the reader is from a different time period and gets transported into the 'Assassination Classroom' world. They then have to adapt to the strange situation of trying to assassinate a teacher while also dealing with the modern - day school life. This could lead to a lot of humorous and heartwarming moments as they interact with the characters.
One interesting plot could be a gamer who gets transported into the Assassination Classroom world and uses their gaming skills to outwit the students in assassination attempts. For example, they might use strategic thinking from real - time strategy games.
Here's a plot. Nagisa decides to take a break from the assassination classroom and goes on a solo journey. During this journey, she meets new people who teach her different skills and ways of thinking. When she returns to the class, she has a new perspective and is able to contribute in ways she hadn't before. Another idea is that Nagisa gets involved in a mystery within the school that has nothing to do with assassinations at first, but as she digs deeper, she realizes it's connected to a larger threat that the class will eventually have to face. And then there could be a plot where Nagisa has to compete in a school - wide competition against other students, and she has to use her assassin skills in a non - lethal way to win.