The unique aspect could be the power - up Naruto gets. As a celestial spirit, he might have access to otherworldly powers that are different from his normal ninja skills. For example, he could have the ability to teleport between celestial realms, which would add a whole new dimension to his adventures.
I'm not sure about a specific 'Naruto is a celestial spirit' fanfic, but you can try searching on fanfiction.net. There are tons of fanfics there, and you might find one that suits your taste. Just use the search bar and type in 'Naruto is a celestial spirit' and see what comes up. You may have to dig through a few to find a really good one, but it's worth the effort.
One great 'Naruto Celestial Spirit' fanfiction is 'The Celestial Ninja'. It combines the concept of Naruto's world with the idea of celestial spirits in a really interesting way. The characters are well - developed, and it has some exciting plot twists.
One possible story could be that Sakura Haruno discovers a hidden magic that allows her to transform into a Celestial Spirit. She might first struggle with the new powers and form. For example, she could find it difficult to control her new celestial body, which might be made of stardust or pure energy. As she adapts, she could use her skills as a ninja, like her quick reflexes and strategic thinking, in the celestial realm. Maybe she teams up with other celestial spirits to fight against a common enemy that threatens both the celestial world and the ninja world she comes from.
Yes, there are some out there. You can try searching on fanfiction websites like FanFiction.net or Archive of Our Own. Just type in 'Naruto is a Celestial Spirit' in the search bar and you'll likely find some interesting works.
One possible plot could be that Naruto is somehow transported to the world of celestial spirits and has to find a way back home. Along the way, he discovers new powers and makes friends or enemies among the celestial spirits.
These fanfictions often change the relationships between characters. Maybe Naruto forms a special bond with a celestial spirit, which alters his interactions with his friends and enemies. It can also lead to new alliances and rivalries within the Naruto universe. Moreover, they can explore different aspects of the Naruto world's mythology. By bringing in celestial spirits, it might dig deeper into the spiritual side of the Naruto world, like how these spirits are related to the chakra system or the history of the ninja clans.
Supreme Fairy was a game based on ancient Chinese mythology, including web games, mobile games, and novels. In the game, players could play the role of immortal cultivators and experience the fantasy world of the immortal world. The Supreme Celestial Spirit had a unique ability to sense the fate of living beings and predict future changes. It was a respected existence in the immortal world, admired and pursued by countless immortal spirits. It was said that the Supreme Immortal Spirit had saved countless living beings from disasters and protected the weak from harm. The game also had a rich variety of unique gameplay, such as Spirit Forge Destiny, Defying Heaven and Changing Fate, and making immortal friends on the path of cultivation. The Supreme Fairy's graphics were exquisite and the combat system was exciting, bringing the players a stunning world of Xianxia.
In the 'lucy becomes a celestial spirit fanfic', perhaps Lucy discovers a hidden power within herself that has a connection to the celestial spirits. As she tries to understand this power, she gradually takes on the characteristics of a celestial spirit. She could start having the ability to communicate with them on a deeper level and even access their powers in a unique way.
There are quite a few interesting Naruto and Fairy Tail celestial spirit fanfictions out there. One I remember had Naruto somehow being able to summon Fairy Tail's celestial spirits. It was really cool to see how the different powers from the two universes interacted. Another great one involved the characters from both series teaming up to protect the celestial spirit world which was under threat from a common enemy.