Other possible characters could include the elders of Konoha. They could be sitting in a special area, watching the parade and commenting on how far the village has come. Iruka Sensei would also be present, cheering on Naruto and the other students. And there could be some new characters created specifically for the fanfiction, like a mysterious figure who seems to be guiding the flow of the parade.
Naruto, of course, is a must. Then there could be Sasuke. He might be a bit reluctant to participate at first but gets drawn into the festive mood. Sakura would also be there, perhaps helping to organize things. Kakashi could be lurking around, keeping an eye on things in his laid - back way.
In a Naruto night parade fanfiction, it could involve a magical or spiritual night parade. Naruto discovers that there are spirits of the past Hokages participating in the parade. He has conversations with them, getting valuable advice on how to further protect the village and become a better ninja. The parade could also be a way to celebrate a new era of peace in the ninja world, with Naruto as the central figure leading the celebration.
It could be an evil shinobi from Naruto's world who has also ended up in the Death Parade world and is trying to corrupt the system. He wants to ensure that all the souls are sent to the void or something worse, just for his own amusement or power - hungry desires.
I'm not entirely sure about all the main characters, but there are some key ones involved in the judgment process.
In 'the black parade story', the main character is the one facing death. There may not be a lot of clearly defined other 'characters' in a traditional sense. But you could consider the memories, the regrets, and the different aspects of the afterlife as almost like characters that interact with the dying protagonist. For example, the memories that come back to the patient are like characters in their own right, as they play a role in the patient's final journey of self - reflection and coming to terms with death.
One of the most popular characters to write about is Nona. She has a mysterious air about her and her position of power in the afterlife gives her a lot of influence. Fanfiction can explore her motives and her plans for the future of the afterlife. Also, Ginti is often written about. His more volatile nature compared to Decim and his own unique style of running death games can be the focus of many stories.
Well, it's likely that we'll see Naruto's sensei, Jiraiya, in this fanfiction too. He could have known about Naruto's 'son of nature' aspect all along and left some clues or teachings for Naruto to discover later. There could also be some ancient shinobi who had a similar connection to nature in the past and their spirits or legacies could play a part. And don't forget the animals! Maybe a giant eagle or a group of intelligent foxes could be characters that assist Naruto in his adventures related to his nature - based powers.
Obviously Naruto himself. And Artemis from Greek mythology. There could also be Naruto's friends like Sasuke and Sakura. Maybe some of the Greek mythological creatures or gods might make an appearance too, like Apollo, Artemis' brother, who could be either an ally or an adversary.
There might be some of the younger ninjas in the village. They could look up to Naruto as he masters the basics. Characters like Konohamaru could be there, eager to learn from Naruto. And perhaps some of the older, more experienced ninjas like Jiraiya could make an appearance to give Naruto some special advice on the importance of basics.
Obviously Naruto himself. There could also be the temple's caretaker, an old wise man or woman who guides Naruto in his stay there.
Obviously Naruto himself is a central character. Then there could be female characters like Sakura, Hinata, and Ino who could be part of the harem in a demon - influenced version. There might also be original demon characters created specifically for the fanfiction, such as a powerful demon queen who takes an interest in Naruto.