One common theme is the struggle for self - identity. A man might be confused about who he really is, like in 'The Catcher in the Rye' where Holden Caulfield is trying to figure out his place in the world. He battles his own insecurities and the false personas he feels society forces on him.
One possible reason could be the burden of his past. Naruto has faced a lot of hardships and the memories might be overwhelming him, making him want to be alone. For example, the loss of his master Jiraiya might have left a deep scar, and he might feel that isolating himself is the only way to deal with that pain.
Maybe he feels a sense of guilt. For example, if something bad happened in the village that he blames himself for, even if it wasn't really his fault. He could exile himself as a form of self - punishment. He has always been very hard on himself when it comes to the well - being of the village and his friends.
One common theme is self - discovery. In these stories, the characters often start off not fully understanding themselves and through their internal struggles, they come to learn more about their true nature. For example, in 'The Strange Case of Dr. Jekyll and Mr. Hyde', Dr. Jekyll discovers the dark and hidden parts of himself that he didn't know existed before creating Mr. Hyde.
One famous 'Man vs Himself' short story is 'The Strange Case of Dr. Jekyll and Mr. Hyde' by Robert Louis Stevenson. In this story, Dr. Jekyll creates a potion that unleashes his alter ego, Mr. Hyde, representing his inner dark side. It shows the struggle within a man as he battles his own repressed desires and the duality of human nature.
In 'Fight Club', the unnamed narrator has an internal struggle. He is disillusioned with his consumer - driven, meaningless life. He creates Tyler Durden as an alter - ego, and then has to fight against the chaos and destruction that Tyler represents while also dealing with his own self - loathing and search for identity.
In some versions of fanfiction, Naruto might use a new and powerful sealing jutsu that he has either created or learned specifically for this purpose. It could be a jutsu that combines his Uzumaki heritage's sealing knowledge with his own unique chakra control.
One challenge is controlling the amount of natural energy. It's not easy to find the perfect balance. Too much and he could turn into a statue or something similar. Another is that he doesn't have a proper teacher to correct him immediately. He has to rely on his own instincts and the limited knowledge he has about senjutsu.
Jiraiya could still play a role. Even if Naruto is raising himself, Jiraiya might cross paths with him and see his potential. He could offer some sporadic guidance without fully taking Naruto under his wing.