One popular natsu training trip fanfiction might be 'Natsu's Epic Training Adventure'. It could detail his growth in strength and new magical abilities he discovers during the trip.
We could expect to see Natsu encounter different magical creatures and environments during his 10 - year trip. He could be in a land full of ice - based magic and have to adapt his fire magic to survive. This would lead to some really interesting battles and power - up moments for him. And of course, he might come across some lost or hidden magic spells that he could bring back to Fairy Tail.
Well, he could meet some old friends or foes. Maybe he runs into an old enemy who has also been training and they have a rematch which pushes Natsu to new limits. Or he meets an old friend who gives him some valuable advice on how to control his magic better during this trip.
Well, perhaps Natsu could return with new and powerful fire - based magic skills. He might have faced some really tough opponents during the 10 - year trip and learned how to overcome them. This could make him even more of a force to be reckoned with in the Fairy Tail guild.
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.