Obviously, the 5th Hokage herself. Then there would probably be Naruto, as he is a central character in the Naruto universe. Sakura might also be there, as she is one of Naruto's closest friends. And Kakashi could make an appearance, given his importance in the story. Shikamaru, with his intelligence, could also be involved, perhaps as an advisor to the 5th Hokage.
The 5th Hokage is a must - have in this fanfiction. Naruto is very likely to show up since he has a connection to the village and its leaders. Ino could be there too, maybe she helps the 5th Hokage with some intelligence - gathering. Sai might be involved as well, perhaps on a mission related to the 5th Hokage's plans. And of course, the elders of the village would likely play a role, either as supporters or as antagonists depending on the plot.
Obviously, Naruto himself is central. His family like Hinata and Boruto would be very likely to be involved. Sasuke is also a key character as Naruto's friend and ally. Kakashi, being Naruto's former teacher, could also play a role. Shikamaru, as Naruto's advisor, would be important in any political or strategic situations. And then there are the other members of the Konoha 11, like Sakura who could be involved in medical support or combat situations if needed.
Naruto himself could be a likely candidate. Given his strength, leadership skills, and his dream of uniting the ninja world, he would make a great 6th Hokage.
Obviously Naruto himself is very likely to appear. He is the main character after all. Sasuke would also be a common character as his relationship with Naruto is so central to the story. Then there are the important figures like the Hokages, especially the ones like Minato and Hashirama who had a big impact on Naruto's life. And of course, characters like Kakashi who played a major role in Naruto's growth.
Sakura would be very likely to appear. She's Naruto's friend and has always been an important part of his life in Konoha. Kakashi too, as Naruto's former sensei. He would be interested in Naruto's growth and return. His friends like Shikamaru, who is smart and has always been there for Naruto in different situations. And of course, Iruka - sensei, who was like a father figure to Naruto in the beginning. He would be overjoyed to see Naruto come back home.
Sasuke could also be a main character. Even though he has his own path, his relationship with Naruto is so deep that he would surely be involved in Naruto's life as the Hokage. He might offer his support or advice when Naruto faces difficulties. And Kakashi, as Naruto's former teacher and the previous Hokage, could also be a key figure in the story.
Sasuke would be a likely character to appear. Since he and Naruto have a deep connection, Sasuke might cross paths with Naruto during his wanderings, either as an ally or an antagonist depending on the plot.
Well, Naruto himself is likely to be there as he is an important part of the Naruto universe. Sakura might also be a common character. Since she has a long - standing relationship with Naruto and other characters in the series. Hinata could also be featured as she has her own connection to Naruto. These characters can be involved in the 'lemon' aspects, like perhaps a love story between the 6th Hokage and one of them.
Sasuke could also be a possibility for the 6th Hokage in the fanfic. He has grown stronger over the years and his unique perspective on the ninja world could bring new ideas to the leadership of the Hidden Leaf. He might start off as a controversial choice but prove himself through his actions in protecting the village and making tough decisions.
Obviously Naruto himself. Since he is the one going to the past, he would be the central character. His younger self would also be important as he would interact with his future self.
The other Konoha 11 members would likely be involved too. They might be split in their opinions. Some would firmly stand by Naruto, while others might be swayed by the village's reasons for denying him. Hinata, for instance, would probably be one of Naruto's biggest supporters and might even try to fight against the decision in her own way.