Maybe Inner Moka has to go to the Naruto world for some reason, like to find a rare ingredient for a potion that only exists there. Naruto helps her navigate his world and in the process, they learn about each other's cultures and powers. Along the way, they also have to face some of Naruto's enemies who are interested in Inner Moka's vampire abilities.
One idea could be a crossover where Naruto finds himself in the world of Inner Moka Lemon. He could team up with her to fight a common enemy that threatens both their worlds. Maybe an evil force that wants to steal Inner Moka Lemon's powers and use them to take over Naruto's world as well.
One idea could be Tsukune and Inner Moka going on a magical adventure in a hidden realm. They might encounter strange creatures and have to work together to overcome obstacles. Another plot could be a mystery where they try to solve a strange occurrence in their school that seems to be related to the supernatural world they inhabit. And perhaps a plot where they get lost in time and have to find their way back while also dealing with their feelings for each other.
One idea could be a story where Vampire Naruto, with his unique vampiric abilities like super speed and enhanced senses, teams up with Inner Moka to fight a common enemy. Maybe a powerful dark force that threatens both their worlds. They could combine Naruto's ninja skills and Moka's vampire powers in epic battles.
One idea could be a crossover where Naruto somehow ends up in the world of Rosario + Vampire and meets Inner Moka. Maybe he helps her in a battle against some powerful demons and in the process, they learn from each other's fighting styles. For example, Naruto could show Inner Moka how to use his shadow clone jutsu in creative ways during combat.
A fanfiction could also be based on Inner Moka being curious about Naruto's world. She decides to visit it, with Naruto as her guide. Along the way, they face various challenges, like dealing with people who are afraid of Inner Moka's vampiric nature. Naruto has to use his skills to protect her and show his world that she means no harm.
Perhaps a story where Moka and Akasha are transported to the Naruto world. They are initially confused but then start to adapt. Moka could use her vampire allure to charm some of the ninja, which causes some chaos. Akasha, on the other hand, tries to find a way back home. Naruto befriends them and helps them understand the ways of his world. Along the way, they uncover a conspiracy in the Naruto world that is related to a mysterious lemon - scented substance that has strange effects on ninja and vampires alike.
One plot idea could be that Vampire Tsukune and Inner Moka have to team up to fight a new and powerful enemy that threatens the entire monster school. They start to train together and during this time, they discover new powers within themselves and also grow closer on an emotional level.
Naruto might be initially confused by Inner Moka Lemon's powers and appearance. But his friendly nature would make him quickly try to befriend her. He could ask her a lot of questions about her world and abilities.
One idea could be a story where Naruto, as a vampire, accidentally stumbles into the world of Inner Moka. He initially struggles to adapt to the new and somewhat strange rules there. For example, he has to deal with the different power dynamics among the characters in that world. As he and Inner Moka interact more, they start to realize that they have more in common than they thought, like their strong wills and determination to protect those they care about.
You can try fanfiction websites like FanFiction.net or Archive of Our Own. They usually have a wide variety of fanfictions, including ones related to Naruto and Inner Moka Lemon. Just use their search functions to look for specific stories.