A possible plot is that the Great Ninja Wars catch Ainz's attention. He decides to observe from a distance at first. But as the wars start to cause more destruction than he expected, he steps in, using his powerful magic. This throws the ninja world into chaos as they've never seen such power before. Some ninja clans might see him as a threat and try to eliminate him, while others might try to ally with him for his power.
In an 'Overlord x Naruto' fanfiction, a great plot could be that Ainz is summoned by a rogue ninja group who wants to use his power to take over the Hidden Villages. Ainz, being his cautious self, decides to play along while secretly planning to take over the whole world for himself. Naruto and his friends then have to figure out how to stop this new, extremely powerful enemy who seems to have an army of undead at his command.
One idea could be that Ainz Ooal Gown somehow ends up in the Naruto world. He could start by trying to understand the new world's power system. Maybe he'd initially be mistaken for a powerful jutsu user or a new type of tailed beast. Another plot could involve Naruto's friends being curious about Ainz's undead minions and trying to befriend them, while Ainz is cautious as he doesn't fully trust the inhabitants of this strange new world.
One idea could be that Naruto is somehow transported to the Overlord world and his unique abilities draw the attention of various female characters, leading to a harem situation. Maybe his ninjutsu skills are seen as a form of magic there.
A third idea is a fusion of the two worlds. The shinobi villages and Nazarick could form a trade or knowledge - exchange system. Characters from both sides would have to learn about each other's cultures and abilities. This could lead to some really fun interactions, like Albedo trying to learn ninjutsu from Kakashi, or Sasuke being intrigued by the power of the Supreme Beings in the Overlord world.
One idea could be that the Avengers are transported to the Overlord's world. They have to figure out how to get back while also dealing with the power dynamics and strange creatures there. Maybe they form an alliance with some of the non - evil characters in the Overlord world to find a way home.
One idea could be that the demon overlord has a hidden past with Naruto's family. Maybe he was once an ally but was betrayed, and now he's back for revenge while Naruto tries to understand the truth.
Maybe Percy and Albedo could embark on a journey to find a rare magical item that is said to have the power to change the balance of power in the Overlord world. Along the way, they learn about each other's cultures and powers, and their relationship deepens from mere acquaintances to close friends or even something more. For example, Percy could teach Albedo some of his combat tactics, while Albedo could introduce Percy to the complex magic system of the Overlord world.
One interesting plot could be exploring the backstories of the minor characters in the Overlord game world. For example, the lives of the villagers who interact with the powerful overlord character.
A plot could revolve around Sesshomaru being intrigued by Naruto's determination. Sesshomaru decides to train Naruto in some of his own combat techniques, which Naruto adapts to his own fighting style. In return, Naruto shows Sesshomaru the value of friendship and loyalty within a village. This could lead to Sesshomaru having a change of heart about his own solitary ways. Also, they could team up to face a common foe from Sesshomaru's world that has somehow entered the Naruto universe.
One idea could be that Naruto and Kashuina meet during a mission outside of Konoha. They start off as rivals, constantly trying to outdo each other in combat skills. But as they face various challenges together, they gradually develop a mutual respect and then deeper feelings. Another plot could be set in a post - war scenario where Naruto, now a hero, meets Kashuina who has a unique ability to heal the psychological scars of the war - torn ninjas. Their interaction then leads to a romantic relationship. And a third idea is that they are both students under a new sensei who pairs them up for special training. During this training, they discover things about each other that they never knew before and fall in love.
One idea could be Naruto being sent to the world of Death Note. He could use his ninja skills to try and outwit Light Yagami. Maybe he would initially be confused by the Death Note's power but then use his determination to stop Light from his killing spree. Another plot could involve Naruto meeting the Shinigami. He might learn about the balance between life and death in this new context and try to find a way to bring some of his ninja world's values to this strange new world.
Perhaps Naruto and Lala meet during a mission where Naruto is sent to a different dimension. Lala, being from an alien world, is intrigued by Naruto's determination and they form an alliance to face a common enemy in that dimension. Their different powers and abilities complement each other, and as they work together, they start to develop feelings for each other.