Another idea is that Naruto's kitsune heritage is somehow linked to an ancient prophecy. This prophecy states that he and Sasuke are fated to either save or destroy the ninja world together. As they journey together, they start to discover the true meaning of the prophecy and how their relationship plays a crucial role in it.
One idea could be that Naruto, with his kitsune powers, and Moka end up in a parallel dimension where they have to work together to find a way back home. They face strange creatures and have to learn about each other's abilities along the way.
One idea could be that Naruto, in his Kitsune form, discovers a hidden power within the Fem Kyuubi that they must learn to control together to defeat a new and powerful enemy. For example, a dark sorcerer who wants to capture the Kyuubi's power for his own evil deeds.
A plot could involve Itachi coming back to life and trying to make amends with Sasuke while also having to deal with Naruto's newfound power. Itachi sees the bond between Naruto and Sasuke and tries to help them strengthen it further for the sake of the Hidden Leaf Village. He could train them in some of his unique jutsu.
One idea could be Naruto, as a kitsune, having to protect Hinata from an ancient evil that targets her because of her special Byakugan powers. The kitsune powers of Naruto could add an interesting twist to the battles and their relationship.
Another interesting plot idea is that a powerful Kitsune artifact from Naruto's world is lost in the RWBY universe. Naruto travels there to find it and in the process, gets involved in the ongoing battles and politics of the RWBY world. He forms strong bonds with the RWBY characters as they all strive towards the same goal of protecting their respective worlds.
One idea could be that Naruto discovers a hidden Kitsune realm. There, he meets a powerful Kitsune who offers to train him in unique chakra control techniques. This could lead to Naruto having new abilities and a different perspective on his ninja skills.
One plot idea could be a Kitsune Anbu agent who has a special mission to protect Naruto but has to hide their true Kitsune nature from him at first. Another could be a Kitsune Anbu being sent to infiltrate an enemy organization that is targeting Naruto and his friends. Or perhaps a story where a Kitsune Anbu discovers a long - lost secret about Naruto's family that has been hidden by the Anbu for years.
One idea could be a story where a young ninja discovers they have the Kitsune bloodline and has to hide it from their village at first because of the superstitions surrounding it. They then gradually learn to control their powers with the help of an old hermit who has knowledge of the Kitsune's secrets.
One interesting plot idea could be a crossover where a Kitsune from the Naruto universe ends up in the Fairytail world. Maybe the Kitsune has unique powers that are both ninja - like from Naruto and magical like in Fairytail. They could team up with the Fairytail guild members to fight a common enemy, like a dark wizard who is trying to steal the Kitsune's chakra for some evil spell.
A possible plot idea is that the kitsune assassin is part of a secret organization that has been observing Naruto for a long time. They believe Naruto has the key to unlock a great power that could either save or destroy the ninja world. So, the assassin is sent to either retrieve this 'key' from Naruto or eliminate him if he can't be controlled. Along the way, the kitsune assassin starts to question their mission as they get to know Naruto better.