It could be due to the current situation in the village. There might be threats that required Naruto to stay. Tsunade, as the Hokage, had to consider the overall safety and stability of the village. So, she denied Naruto's request for the training trip to ensure he was available in case of any emergency.
In the fanfiction's training trip, Naruto may encounter some spiritual beings. These beings could be related to the origin of chakra or some long - forgotten ninja legends. Interacting with them would be a very different experience for Naruto. He would have to use not only his physical skills but also his wits and understanding of the ninja world's deeper mysteries to communicate with them. This could lead to a major transformation in his ninja journey, as he delves deeper into the spiritual side of the ninja arts.
He could meet an old hermit ninja who imparts his wisdom and knowledge to Naruto. This hermit might have been living in seclusion for years, but seeing Naruto's potential, decides to teach him things not found in normal ninja training.
Well, in this fanfiction's training trip, Naruto may come across different clans with their own exclusive fighting styles. He could engage in friendly sparring matches with their members, which would not only enhance his combat abilities but also his understanding of different cultures within the ninja world. He might also find some ancient artifacts that hold great power and have to figure out how to use them properly without being corrupted by their power.
Naruto might meet some foreign ninjas from far - off lands that have completely different fighting styles. These ninjas could teach him new ways to use his chakra and improve his combat abilities. He may also encounter some mysterious hermits living in the mountains or forests who possess great wisdom and unique jutsu. They could guide him on his journey of self - improvement and give him valuable advice on how to become stronger as a ninja.
He could meet other sannin. Maybe he stumbles upon Orochimaru who is on some secret mission. This encounter would be full of danger and Naruto would have to use all his skills and wits to survive.
He could learn new and powerful jutsus. For example, he might discover some unique wind - style jutsus that are not in the original series. This would make him more formidable in combat.
Well, Naruto might learn some new and powerful jutsus during the training trip. Maybe he meets some unique characters who teach him special skills or give him valuable advice.
There could be new characters created specifically for this fanfiction. For instance, an old hermit who lives in the mountains where Naruto is training and has some ancient knowledge of ninjutsu. Or perhaps a group of rogue ninjas who try to disrupt Naruto's training. Also, characters from other villages that Naruto might interact with during his travels, such as a young ninja from the Sand Village who is also on a similar training journey.
Well, Naruto himself is obviously a common character. Sasuke also often makes an appearance, either as a rival still or as someone who has a change of heart and decides to join Naruto's training. Kakashi might show up too, to give some guidance or check on Naruto's progress.