One important ghost could be the previous Hokages. They have a lot of knowledge and wisdom about the village and its secrets. Naruto seeing them could be a way for him to get some really valuable advice on how to deal with the current threats to the village, like a new powerful enemy or internal political issues.
There was no clear conclusion as to whether seeing the Black and White Ghosts was a good thing or a bad thing. According to the legends, meeting the White Impermanence could bring good fortune, while meeting the Black Impermanence could bring disaster. However, these were just folk legends and were not supported by scientific evidence. Therefore, he couldn't be sure whether it was a good thing or a bad thing to see the Black and White Ghosts.
It could affect the plot by making Naruto more cautious. Since he can see ghosts, he might be constantly on edge, not knowing if a new ghost is a friendly one or a threat. This could lead to him making different decisions in battles or in his interactions with other characters. He might also try to avoid certain places where there are a lot of ghosts, which could change the course of his adventures.
The Black and White Ghosts were gods that specialized in catching evil ghosts. Their duty was only to catch ghosts and would not disturb ordinary people. Therefore, if you see the Black and White Ghosts, you don't have to be afraid. If you are afraid, you can immediately recite the name of Buddha or Guan Yin Bodhisattva to ease your fear. However, there was no clear answer in the search results. Therefore, I don't know how to answer this question.
The Black and White Impermanence didn't really exist. They were just a pair of gods in Han folk culture, characters in myths and legends. Therefore, no one could see the Black and White Ghosts because they only existed in legends.
Romance male protagonists who could see ghosts were usually people with special abilities or superpowers. This kind of plot often involved the male protagonist's contact and adventure with ghosts, and it was often accompanied by the support and help of the female protagonist. Such a plot would usually make the readers feel nervous and excited, and it would often trigger the readers to think about human nature and morality.
I recommend the book Guide to the Night Return to you. The male protagonist gained the ability to attract evil people in an accident. Every night, there are all kinds of bad people following him. Although you can't directly see ghosts or borrow ghosts, this ability is similar to the special ability of having ghosts as companions. I hope you like it.
Kids can see stories because they have a natural curiosity and a need for entertainment and learning. Stories capture their imagination and help them understand the world around them.