Sure. There are various fanfiction platforms out there where you can find Naruto stories with the Kusanagi. Some writers might be inspired by the idea of Naruto getting his hands on such a powerful and legendary weapon. They could write about how it changes his abilities or his standing in the ninja world. It could also be a part of a crossover story, where Naruto uses the Kusanagi in a different context than the original Naruto story.
The idea of 'Harry Potter uses Kusanagi' in fanfiction is likely a product of the writer's imagination to break the boundaries of the original Harry Potter world. Kusanagi has its own set of legends and properties. By having Harry use it, the fanfiction author might be trying to show how Harry can adapt to and utilize something completely foreign. It could lead to all sorts of interesting scenarios, like battles against new enemies or the exploration of uncharted magical territories.
Naruto would probably be very curious about Motoko's cybernetic enhancements. He might constantly ask her questions and be in awe of her abilities. Motoko, on the other hand, would likely be initially intrigued by Naruto's exuberance and then start to analyze his ninja skills scientifically.
You can start by looking on popular fanfiction websites like FanFiction.net or Archive of Our Own (AO3). These platforms have a large collection of Naruto fanfictions, and you can use the search function to specifically look for stories that involve the Kusanagi. Just type in relevant keywords like 'Naruto' and 'Kusanagi' and browse through the results.
I'm not sure if there are extremely popular ones specifically with that exact concept. Fanfiction is a vast world and while there might be some that incorporate this idea, it may not be mainstream. However, it could be a hidden gem in the fanfiction community that only a few dedicated readers have discovered.
One possible plot could be that Harry Potter, through some magical mishap, ends up in a world where Kusanagi exists. He might use his magic to help Kusanagi in a battle against a common enemy. For example, Harry could use spells like 'Expelliarmus' to disarm Kusanagi's foes.
Harry Potter and Kusanagi are the central characters. Harry, being used to the magical society of Hogwarts, would have to adapt to the world of Kusanagi. And Kusanagi would have to come to terms with the existence of magic in the way Harry uses it. There could also be other supporting characters from both their worlds. Maybe some of Harry's friends from Hogwarts like Hermione could make an appearance and offer her vast knowledge to help in the situation. Or there could be characters from Kusanagi's side who are initially skeptical of Harry but later come to respect him as they see his powers at work.
One idea could be a crossover where Naruto's world of ninjas and Motoko's cybernetic reality collide. Maybe Naruto is transported to Motoko's world and has to learn to navigate the high - tech environment while Motoko tries to understand his strange chakra powers.
He might meet the future versions of Naruto and Sakura. Their relationship with him could be very different in the future, perhaps they are now leaders of the village and Sasuke has to adjust to their new status.