A cool Kamen Rider Ryuki crossover fanfiction idea would be to cross it with a superhero universe like the Marvel or DC universe. Picture Ryuki fighting alongside Spider - Man or Batman against a powerful villain. Or perhaps a crossover with a science - fiction series like Doctor Who. The time - traveling aspect of Doctor Who could add an interesting dynamic to the Ryuki story.
One idea could be a crossover with other Kamen Rider series. For example, Ryuki characters interacting with those from Kamen Rider Decade. They could team up to fight a common enemy that has the ability to travel between different Rider worlds. Another idea is a crossover with a popular anime. Maybe Ryuki riders in the world of Naruto, where they have to adapt their fighting styles to the ninja world.
A more complex idea could involve the Mirror World from Ryuki. In the fanfiction, the RWBY characters could be accidentally pulled into the Mirror World. There, they meet the Riders from Ryuki and have to figure out a way to escape. Along the way, they learn about the rules and dangers of the Mirror World, and also discover some secrets about their own powers.
One idea could be exploring an alternate universe where the riders form different alliances. For example, some of the more antagonistic riders team up against a common threat that is far more powerful than any single rider. This could lead to interesting character development as they have to put aside their differences.
Another plot could involve a misunderstanding between the Kamen Rider Ryuki and Dragon Knight characters that leads to an initial battle between them. But as they fight, they start to realize they have more in common than they thought and end up joining forces. For example, they could discover that a shadowy organization is manipulating events to keep them at odds.
Well, from the Kamen Rider universe itself, characters from Kamen Rider Blade could be great for a crossover. Their different powers and personalities would create interesting interactions with the Ryuki characters. Another suitable character could be Kiva. His vampire - like nature and unique fighting style would add a new flavor to the Ryuki crossover.
One idea could be a crossover with another Kamen Rider series like Kamen Rider Decade. Blade could find himself in Decade's world, where he has to team up with Decade to fight a common enemy that threatens both their worlds. This would bring a lot of action and an interesting dynamic between the two different Kamen Riders.
One idea could be a crossover with another Kamen Rider series like Kamen Rider W. They could team up to fight a common enemy that is causing chaos in both of their worlds. Maybe the Dopants from Kamen Rider W are working with some of the Horoscopes from Kamen Rider Fourze.
One idea could be a crossover with other Kamen Rider series, like Kamen Rider Decade. The two riders could team up to fight a common enemy that has the ability to travel between different rider worlds. It would be exciting to see how their different fighting styles and powers combine.
One idea could be to cross over a Kamen Rider OC with a well - known anime character. For example, a Kamen Rider OC with Naruto. The OC could use their Kamen Rider powers in the Naruto universe, facing off against ninjas. Another idea is to have a crossover with a superhero from Western comics. The Kamen Rider OC might team up with Spider - Man to fight a common enemy in New York City.
One idea could be a crossover with another Kamen Rider series like Kamen Rider Kuuga. They could team up to fight a common enemy that is stronger than what they've faced individually. For example, a new type of unknown that has the powers of both Gurongi and the Lords. Another idea is a crossover with a superhero from the Marvel or DC universe. Imagine Agito and Spider - Man working together in New York City, with Agito's powers impressing Spider - Man and them learning from each other's combat styles.
A crossover with Kamen Rider Zi - O could also be really cool. Zi - O travels through time, so he could accidentally disrupt the timeline in a way that affects Ghost's world. Ghost might have to team up with Zi - O to fix the timeline while also dealing with the enemies that are taking advantage of the time - chaos. They could encounter different versions of themselves from alternate timelines and have to figure out how to make things right.