Iruka would definitely be involved. He has always been like a father figure to Naruto. Iruka would be concerned about Naruto's new power and try to talk to him about the potential risks. Also, characters from other villages, such as Gaara from the Sand Village, could interact with Naruto. Gaara, who has his own experience with inner darkness, might be able to relate to Naruto and offer his unique perspective on how to handle this new power.
Sasuke would likely be one of the main characters to interact with Naruto. Given their complex relationship, Sasuke might be either supportive or skeptical of Naruto's newfound power. Sakura could also be involved, perhaps trying to heal Naruto if the dark power has negative effects on him. Kakashi would surely step in as well, using his wisdom to guide Naruto and make sure he doesn't lose himself in the darkness.
Sasuke would be a likely character to interact. Given their complex relationship throughout the Naruto series, Sasuke might be suspicious or intrigued by Naruto's control over Zetsu. Their interactions could range from confrontations to reluctant teamwork.
Obviously, Koyuki herself would be a main character to interact with Naruto. She might show him around her place, introduce him to her people. Also, any of her loyal guards or advisors could interact with Naruto. They could be initially suspicious of him but then grow to trust him as they see his good intentions.
Sasuke would be a likely character. Their rivalry could take on a new dimension as Naruto's super intelligence might make Sasuke more intrigued or even a bit jealous. They could have more complex conversations about strategy and the future of the ninja world.
The plot might involve Naruto exploring a darker side of his power. Maybe he's pushed to the edge by some great threat and decides to use the 'darkness' within him, which could be some sort of forbidden chakra or a new, shadowy ability. This could lead to him having to face his friends who are initially against his new path but later come to understand his reasons.
Naruto and Aang would be the most obvious ones. They are the main characters in their respective worlds.
Obviously, Sasuke would still be a major character she interacts with. Their relationship could be even more complex now that Naruto is a girl. Sakura might also have a different dynamic with Naruto. Instead of seeing her as a rival for Sasuke's attention, they could become closer friends and train together more often.
Kakashi could also be a character involved in interactions. His calm and observant nature would make him a good mediator between the two groups. He might be interested in learning about the monster musume's abilities and how they could potentially be used in the ninja world. Rock Lee might also be a candidate. His enthusiasm and determination could be an interesting contrast to the monster musume, and he could potentially learn new fighting styles from them or teach them his own.
Iron Man is another candidate. Tony Stark's technology and Naruto's ninja techniques could be a great contrast. They could learn from each other. Stark might be interested in Naruto's chakra - based powers and try to replicate them in some way, while Naruto could be amazed by Stark's high - tech gadgets.
Well, in the 'naruto lifts thor's hammer fanfic', apart from Thor, other Asgardians like Heimdall could interact with Naruto. Heimdall, with his all - seeing ability, might have seen Naruto's worthiness from afar. The Hulk could also be involved. Imagine the chaos if the Hulk got jealous of Naruto having the hammer. And from Naruto's side, Kakashi could be there to guide Naruto on how to handle this new power that comes from a different world.
Kakashi could also play a role. He has been Naruto's mentor for a long time. So, he might have some mixed feelings about Itachi adopting Naruto. He could be suspicious of Itachi's motives at first but then gradually come to understand Itachi's positive influence on Naruto. Their interactions could be really fun to read about, especially when Kakashi tries to give Itachi some advice on how to handle Naruto's wild nature.