His relationship with Sasuke would likely become more harmonious. In life, they had their share of struggles and rivalry. But in death, they could finally let go of their earthly grudges. They might spend time reminiscing about their bond, from their first encounter as rivals to their later alliance.
Perhaps Naruto would use his afterlife to gain new powers or knowledge. Since he was always eager to learn and improve during his life. He might encounter some spiritual beings who teach him unique jutsu or give him insights into the secrets of the ninja world that were unknown during his lifetime. And he could then use this newfound knowledge to help other souls in the afterlife.
He might meet his sensei, Jiraiya. They could have long talks about Naruto's growth as a ninja and Jiraiya could give him more wisdom from the afterlife perspective.
One possible reason could be to protect his family. After the war, Naruto might have made many enemies. By faking his death, he could draw the attention of these enemies away from his family, especially his wife and children. His enemies would think he's no longer a threat and stop targeting his loved ones.
A 'Naruto After Death' fanfiction could show Naruto's journey in the afterlife as a way to bring peace to the souls of those who died with grudges. He could use his unwavering will and the bonds he formed in life to help resolve the negative emotions of these lost souls. He might also meet his parents in the afterlife and finally have a proper family time that was cut short in his living days.
Sakura would be extremely angry at first. She has known Naruto for a long time and would feel betrayed that he didn't trust her enough to tell the truth. But later, she would understand his reasons and might even help him if she could.
Hinata might become more determined. After crying over Naruto's death, she could realize that she needs to be stronger. So she might start taking on more leadership roles in the village, using her Byakugan skills more effectively.
There are many accounts that claim to be true stories about life after death. Some people report near - death experiences where they see a bright light, feel a sense of peace, and even encounter deceased loved ones. However, from a scientific perspective, there is no conclusive evidence to prove that there is life after death. These experiences could potentially be the result of the brain's reaction in extreme situations.
One possible scenario could be that Naruto leaves to train in isolation. He might feel that he needs to become stronger on his own without the guidance of Jiraiya, and so he sets off to find new ways to improve his skills.