A crossover with a slice - of - life anime such as K - ON! would be quite interesting. Imagine the cute and carefree girls from K - ON! suddenly being thrust into the dark and often disturbing world of Higurashi. It would be a contrast of tones, with the light - heartedness of K - ON! clashing with the mystery and horror of Higurashi, leading to some unique character interactions and story developments.
How about a crossover with a fantasy anime like Sword Art Online? The characters from Higurashi could end up in the virtual world of Sword Art Online. They might have to deal with the game's rules and enemies while also bringing their own mystery and backstories from their original world. This could lead to new friendships, rivalries, and of course, lots of action - packed adventures within the game world.
One idea could be to have the characters from both series meet in a mysterious world that combines the settings of Rokkenjima and Hinamizawa. For example, Rika could end up on Rokkenjima during one of the family conferences and use her knowledge from Hinamizawa to try and solve the mystery of the murders there. Another plot could involve Beatrice from Umineko somehow being involved in the Hinamizawa Syndrome events in Higurashi, adding a new layer of mystery and magic to the story.
A crossover with a fantasy anime like Sword Art Online could be very exciting. The Higurashi characters could be trapped in the virtual world of Sword Art Online, and they would have to fight their way through the game while also dealing with the paranoia and mystery that is characteristic of Higurashi. It would be a blend of high - tech and rural horror.
One interesting idea could be a crossover with "Moana". Elsa's ice powers and Moana's connection to the ocean could create a really cool dynamic. Maybe Elsa accidentally freezes part of Moana's ocean and they have to work together to fix it. Another could be with "Tangled". Rapunzel's long hair and her adventurous spirit combined with Elsa and Anna's journey in Frozen 2 would be exciting. Rapunzel could use her hair to help them climb mountains or cross chasms. A third idea is a crossover with "Beauty and the Beast". Belle's love for books and knowledge could help Elsa understand more about her powers and the history of magic in the Frozen world.
A Rambo crossover fanfiction could involve him crossing over into the Star Wars universe. Rambo's guerilla warfare tactics could be interesting in a galaxy far, far away. Maybe he helps the Rebel Alliance in a ground - based battle against the Empire. Or a crossover with the Predator series. Rambo would be a worthy opponent for the Predator, and the fight between them in the jungle could be epic. Also, a Rambo and John Wick crossover would be intense, two highly skilled fighters on the same side or perhaps initially at odds.
One idea could be a crossover with a modern military setting. The Decepticons could be trying to steal advanced military technology. Another is a crossover with a post - apocalyptic world where they are competing with other factions for resources. A third could be a crossover with a magical realm, with the Decepticons trying to harness the magic for their own evil purposes.
One idea could be a crossover with Naruto. Kakuzu could be sent to the Naruto universe and form an unlikely alliance with a shinobi village to fight a common enemy, like the Akatsuki from his own world turned rogue in the new universe. This would create a lot of interesting character dynamics and battles.
Another option is a crossover with 'The Little Mermaid'. The characters from the descendants could meet Ariel and her friends underwater. Evie might be interested in the mermaid fashion and could design new outfits inspired by the underwater world.
Another possibility is a crossover with the world of Naruto. The characters from MHA could participate in the Chunin Exams. Bakugo might be really into showing off his skills in this new and different kind of competition.
One idea could be a Venom crossover with Spider - Man in an alternate universe where they have to team up against a common enemy like Carnage. Another could be a Venom and Deadpool crossover, with their crazy personalities clashing and then somehow working together. Maybe a Venom crossover with the X - Men, where Venom's alien nature causes some interesting reactions among the mutants.
For a Monokuma crossover fanfiction, consider a crossover with 'Final Fantasy'. Monokuma could be a summoned monster by an evil villain in the game's world, causing all sorts of problems for the heroes. He might even try to take over the crystals. A crossover with 'Persona' could also be interesting. Monokuma could enter the Metaverse and start his own 'Palace', recruiting Shadows to enforce his rules. And how about a crossover with 'One Piece'? Monokuma could be a new Warlord of the Sea, using his wacky yet dangerous devices on the Straw Hat Pirates and their allies.