A plot could involve a young ninja who has the ability to communicate with the Nine Masked Beasts. He tries to understand their past and in the process uncovers secrets that could change the Naruto world. This ninja then has to decide how to use this knowledge, whether for good or for personal gain.
One idea could be a story where the Nine Masked Beasts form an alliance to protect the Hidden Leaf from a new, powerful enemy. They set aside their differences and combine their unique powers.
Perhaps a fanfiction where the Nine Masked Beasts are reincarnated in different forms. They no longer have their original powers but instead have new abilities. The story could follow their journey to regain their former strength while also facing the challenges of a world that has changed since their last existence.
Well, for the 'naruto the masked man fanfiction', you could have a plot where the masked man has a secret ability that only Naruto can help him control. This could lead to a unique bond between them. Or perhaps the masked man is from a different dimension and got stuck in Naruto's world, and his actions are a result of trying to get back home. Also, a story where the masked man is a time - traveler and is trying to prevent a future disaster in Naruto's world could be really interesting.
Madara Uchiha could be a great antagonist. His powerful Sharingan and vast combat experience would make him a formidable foe against the Nine Masked Beasts. He could be after their power to further his own plans for the ninja world.
One idea could be that the female tailed beasts team up with Naruto to protect the Hidden Leaf from a new and powerful enemy. They use their unique powers in combination with Naruto's skills to create some really cool battle scenes.
One interesting plot idea could be Naruto having to form a special bond with each tailed beast separately. For example, he might start with the One - Tailed Shukaku and have to understand its past and the pain it has endured. This could involve him entering the tailed beast's mind - scape and facing its inner demons. Another idea is that all the tailed beasts decide to test Naruto's worthiness as the Jinchuriki of the Nine - Tails. They could create various challenges for him, both physical and mental, to see if he can truly handle the power of all the tailed beasts combined. A third plot could be that an ancient evil threatens the world, and only by uniting all the tailed beasts and their powers, with Naruto as the leader, can they defeat it.
One popular plot idea is a masked ninja being a long - lost relative of a main character. For example, they could be related to Naruto and have been in hiding all this time. Another idea is a masked ninja being a spy from another village, with a complex backstory of loyalty and betrayal. Also, there could be a masked ninja who is a time - traveler, coming from the future to change key events in the Naruto universe.
A possible plot is that the Nine - Tail's fury is somehow transferred to other characters in the village. Naruto then has to find a way to reverse it while also dealing with the chaos that ensues. For example, some villagers who receive the fury start attacking each other. Naruto has to use his bond with the Nine - Tail and his understanding of its power to calm them down and bring back peace. It could also lead to a deeper exploration of the relationship between the villagers and the tailed beasts.
Perhaps in the fanfiction, the baby nine - tails gets separated from Naruto for a while. During this time, it has to fend for itself in a world that fears it. It could meet other friendly or hostile creatures and have various adventures before reuniting with Naruto.
One idea could be Naruto having a unique connection with the Nine Tails that allows him to access new forms not in the original series. For example, a form that combines his human features with more fox - like aspects in a more aesthetically pleasing and powerful way.
One idea could be a fanfiction where Naruto has to temporarily transfer the Nine - Tails' power to a fellow ninja to save the village. This would create an interesting dynamic as the other ninja has to quickly adapt to the power and the responsibility that comes with it.
One idea could be Naruto exploring the true origin of the Nine - Tails within his own family history. Maybe his ancestors had a special connection to the Nine - Tails that was long forgotten.