The plot could involve Naruto being assigned as a guardian angel to Konoha. He'd have to use his unique abilities like the Shadow Clone Jutsu in unexpected ways to protect the villagers from unseen and spiritual dangers. Maybe he has to deal with a curse that is plaguing the village from the spirit realm and he uses his new - found angelic powers in combination with his ninja training to break the curse. He could also have a connection with other celestial beings that help him understand his new role better.
Well, perhaps Naruto could be sent to protect a certain village or person. He might use his ninja skills in a new way to fend off threats from the spirit world or other supernatural forces.
In the 'naruto is an angel fanfiction', it could be that Naruto's angel form is a result of some ancient curse or blessing. His friends might be initially shocked but then come to rely on his newfound angelic abilities. He could use his powers to purify the darkness that lurks in the hearts of some of the villains in the Naruto universe, like Orochimaru. He might also be able to create shields of light to protect his village from attacks.
Lily Potter could also be a great candidate. Her love for Harry was so strong. As a guardian angel, she could appear to Harry in his dreams or in moments of great danger, using her motherly love as a shield and giving him advice based on her own experiences in the wizarding world.
Maybe Naruto, as a fallen angel, has lost his powers and is trying to regain them while still in the Ninja world. He could be facing discrimination from both the angels (if they exist in the story's universe) and the Ninja who see him as something different.
Well, one possible plot could be that Naruto is cursed by some dark force and turns into a fallen angel. He might struggle with his new identity, as it goes against his usual positive and energetic self. His friends in Konoha could initially be scared or confused by his transformation, and Naruto has to prove that he's still the same person deep down while also dealing with the new powers and temptations that come with being a fallen angel.
It could be about a doctor who has some kind of special ability or gift that makes them a 'guardian angel' in the medical world. Maybe they can sense diseases before they are diagnosed by normal means.
Well, one possibility is that Naruto, as the Angel of Death, is sent to the ninja world to end the cycle of violence. He might start by targeting those who have caused great harm, like powerful villains. But he could also face moral dilemmas when it comes to people he once knew and cared about. For example, he might have to decide whether to spare a former friend who has turned to the dark side but still has some good in them.
It could be his mother, Lily. Her love was already a powerful protection for Harry, so in the fanfiction, it could be her spirit acting as a guardian angel, using her love to shield him from harm in a more direct and continuous way.
A plot could involve a common enemy that threatens both the world of Angel Beats and the Naruto world. The Akatsuki from Naruto might be interested in the powers that exist in the Angel Beats world. So they start to invade it. The characters from both sides would have to team up. Naruto and Otonashi would lead their respective teams. Hinata could bond with some of the female characters in Angel Beats over their shared experiences of having to be strong in difficult situations. And Kakashi could teach some of the Angel Beats characters some ninja techniques.
Perhaps Naruto discovers he is an angel who has been sent to the Naruto world for a specific mission, but due to some events, he 'falls' and starts to question his purpose. His journey could involve trying to find his place between the angelic realm and the ninja world. He might also have to deal with other angel - like beings who are either trying to bring him back or stop him from interfering in their plans.
One possible plot could be that Naruto discovers he has black angel wings. Maybe it's a result of some ancient curse or a new form of chakra manifestation. He initially struggles to control them, fearing they make him different. As the story progresses, he learns to use the wings' power to his advantage in battles, perhaps even flying to reach enemies quickly or using the feathers as projectiles.