Perhaps Naruto is transported to the world of Unlimited Blade Works and has to learn to use its powers to get back home. Along the way, he could meet characters from that world and form new alliances. He might also bring some of the concepts from Unlimited Blade Works back to his own world and revolutionize the way ninjas fight.
A cool plot could be that a powerful enemy is attacking both the Naruto world and the world of Unlimited Blade Works. Naruto, with his newfound Unlimited Blade Works powers, teams up with characters from both worlds to fight this common foe. He could learn new combat techniques from the Unlimited Blade Works side and combine them with his own ninja skills. This would make for an epic battle - filled fanfiction with a lot of character development and world - building as Naruto tries to bridge the two very different universes.
Perhaps in this fanfiction, Naruto enters the Unlimited Blade Works realm and has to face his own inner demons represented as clones within that world. This would be a great way to explore his character deeper as he battles his fears and insecurities.
Well, there might be some out there. You could try searching on fanfiction websites like FanFiction.net or Archive of Our Own. Just type in the keywords 'Naruto' and 'Unlimited Blade Works' and see what comes up.
Perhaps there is a wish - granting entity in the fanfiction. Naruto, in his quest to protect his village or friends, makes a wish to be able to use any power necessary. The entity grants him the ability to use Unlimited Blade Works. He then has to train himself to master it, which would be an interesting journey as he tries to balance his ninja way with this new, very different power.
One possible plot could be that during a battle, Harry is transported to a realm similar to the one in Unlimited Blade Works. There, he learns the art of Unlimited Blade Works and brings it back to Hogwarts. He then starts training his friends in this new form of combat. Together, they use it to defend Hogwarts against a new, powerful dark force that is immune to normal wizarding spells. The story could explore how they combine traditional magic with the new abilities, and how they face the challenges of using an unfamiliar power.
One consequence could be that his enemies are completely caught off - guard. Naruto's new ability to summon a vast number of weapons at will would change the dynamics of battles. Enemies used to his ninja attacks would now have to deal with a whole new type of assault.
It could be about Naruto discovering a hidden blade - using technique and becoming a master at wielding it in battles against new and powerful enemies.
One idea could be Izuku discovers he has the ability to use Unlimited Blade Works in a moment of extreme danger. He starts training with it secretly, trying to master the different blades and their unique powers.
Naruto himself is always interesting. In this fanfiction, seeing him adapt to the new powers of Unlimited Blade Works and how it changes his fighting style would be fascinating. He might become more strategic and less reliant on brute force.
A unique feature is the combination of two different universes. Naruto's ninja abilities like shadow clones and rasengan blend with Unlimited Blade Works' concept of noble phantasms.
A powerful sorcerer who wants to steal Izuku's Unlimited Blade Works power for his own evil purposes. He could be from a hidden world of magic and have minions that Izuku has to fight through.