Perhaps Naruto enters the Death Parade world in search of a lost comrade. He teams up with the arbiters, reluctantly at first, when he realizes that they have some knowledge about where his friend might be. Along the way, he shows them the power of friendship and loyalty that he has learned in the Naruto universe, and they in turn show him the complex nature of the afterlife in the Death Parade world.
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.
One idea could be exploring the backstories of the characters in more depth. For example, the arbiter's past lives before becoming an arbiter. Another could be creating an alternate ending to the series where different decisions are made during the death games. Maybe a fanfiction where the characters from different death games interact with each other outside of the normal game settings.
The plot focuses on a place where the dead are sent. The main characters interact with the newly - dead souls. The games they play can be cruel and intense. For example, some games test the limits of a person's honesty and loyalty. The light novel also shows how the characters grow or change during these afterlife experiences. It's a story that makes you think about your own actions and how they might be judged if there is an afterlife.
One possible plot could be Naruto discovers a hidden jutsu that allows him to combat the powers of the Death God. He trains hard to master it and then uses it to save his village from a new, powerful enemy who has the ability to control the Death God's powers. Along the way, he has to face his own inner demons and the doubts of his friends.
One idea could be exploring the backstories of the arbiters more in - depth. For example, Decim's past before becoming an arbiter and how it might influence his judgments. Another could be creating a scenario where a new type of soul arrives at the bar that challenges the existing rules of the Death Parade.
One possible plot could be that Naruto somehow gets transported to the Darksiders universe and is mistaken for Death. He then has to adapt to this new, darker world while also dealing with the enemies and challenges that Death would typically face.
A possible plot could be that Naruto has a near - death experience and in that state, he encounters Lord Death. Lord Death offers him a deal: to become his disciple in exchange for the power to protect his loved ones better. Naruto accepts and starts to train under Lord Death. As he learns more about Lord Death's domain and powers, he has to make difficult choices between his old ninja life and this new path. His friends in Konoha start to worry about him as he changes, and there is a struggle to keep his relationships intact while following this new calling.
Maybe Naruto gets transported to the world of Death Knights. He could use his ninja skills in a new way, like combining his chakra with the powers of a Death Knight. For example, his Rasengan could be infused with Death Knight magic.
Well, one possibility could be a crossover where Naruto somehow ends up in the world of Death the Kid. Maybe Naruto's chakra is mistaken for some kind of unique soul energy. And Death the Kid, being the perfectionist he is, might be intrigued by Naruto's unruly and yet powerful nature. They could team up to fight some common enemy that threatens both their worlds.