Kakashi could be a significant supporting character. He could provide Naruto with some advice or even join the battle alongside Naruto for a while. Another possible supporting character could be Hinata. Her gentle presence and belief in Naruto could give Naruto the extra motivation he needs during the fight.
The plot could involve Kakuzu being controlled by a more powerful and evil force. Naruto, after trying to reason with him and failing, has no choice but to kill him. This could also be a part of Naruto's growth, where he realizes that sometimes, in the face of extreme evil, killing is the only option to protect others.
Iruka sensei could be another one. He could be the one who encourages Naruto to become a dentist in the first place. He might also bring in students from the Ninja Academy for dental check - ups, which would help Naruto's practice grow. And of course, Naruto's friends like Shikamaru and Choji could also be there. Shikamaru could use his intelligence to come up with efficient ways to manage the patient flow, while Choji could be the one who tries to make the waiting area more comfortable with his love for food, like suggesting the best snacks for patients to have while waiting.
Shikamaru could be a supporting character. He might be the one who sent Naruto and Sasuke to the bathhouse area as part of a strategic plan for a mission. He could be waiting outside and making snarky comments when they come out. Another could be Sakura. She might be worried about Sasuke being in the bathhouse with Naruto and come to check on them, causing some comical moments.
Kakashi could be a supporting character. He has a connection to both Naruto and Sasuke. He might try to stop Naruto from going too far in his revenge, reminding him of the values he once held. Another could be Hinata. She could be there to support Naruto emotionally, giving him the strength to face Sasuke. Rock Lee might also be involved. He has always respected Naruto and would probably join him in his quest, especially if he believes Sasuke has become a real threat to the ninja world.
Sakura could be Naruto's personal physician or his stylist. Given her intelligence and her skills in the original story, she could play an important role in keeping Naruto in top shape for his shows or making him look his best. She would be the one to patch him up if he gets injured during a stunt or a performance.
One possible plot could be that Kakuzu, with his tough and practical nature, trains Naruto in a very different way from the traditional Konoha style. He might focus more on self - reliance and survival skills. Naruto could learn unique jutsu from Kakuzu related to his earth and water - based techniques.
Sakura could be a main supporting character. As a ninja, she might check on Naruto regularly to make sure he's adjusting well to civilian life. She could also offer medical help if he has any lingering issues from his ninja days.
It could be an original character created just for the fanfiction. Many fanfiction writers like to introduce new characters to add their own unique twists to the story.
Well, it could be a really interesting dynamic. Maybe in the fanfiction, they meet during a mission where they have to team up. Naruto's determination and Kakuzu's skills could make them a formidable pair. As they spend more time together, a romantic connection might develop. Naruto might be attracted to Kakuzu's strength, and she could be drawn to his kind heart beneath the tough exterior.
One possible supporting character could be Naruto's friends from Konoha. They might visit Naruto in Konoka's world and be a bit skeptical at first about his relationship with Konoka. Another could be Konoka's family members. Her father, for example, might be initially hesitant about Naruto but then come to accept him. There could also be some local villagers in Konoka's place who become friends with Naruto and help him adjust to the new environment.