One idea could be that the characters from Battle Royale are transported into the world of Akira. They have to deal with the psychic powers and the chaotic society in Akira's world while also trying to figure out how to get back to their own. For example, the students from Battle Royale might be seen as a threat by the military in Akira's world and have to fight both them and the psychic-powered individuals.
Well, for starters, you can give the Battle Royale characters some of the abilities or traits from the Akira characters. For instance, make one of them have a bit of Tetsuo's instability and power - hunger. Or you could have an Akira character thrown into the Battle Royale situation and see how they use their psychic powers to survive. Maybe they use it to form alliances or to take out threats from a distance.
One idea could be to cross Akira Fudo with a character from another popular anime, like Naruto. Maybe Akira could end up in the Hidden Leaf Village and have to deal with their unique political and ninja challenges while also controlling his devilman powers. Another idea is a crossover with a superhero universe. Akira could team up with Superman, and they'd face off against a common enemy. The contrast between Superman's pure-heartedness and Akira's internal struggle with his demonic side would make for an interesting dynamic.
A possible idea is that Shuya has some special ability that Kazuo wants to learn from. So, Kazuo tries to make a deal with Shuya during the battle royale. Shuya is hesitant at first, but as they face more and more challenges together, they start to trust each other. And this trust might be the key to their survival in the brutal battle royale world.
A crossover with Ghost in the Shell could be really interesting. Alita could meet Major Kusanagi. They could exchange knowledge about their cybernetic bodies and the nature of consciousness. Maybe they'd work together to stop a hacker group that's trying to gain control over all cybernetic beings in both their worlds.
How about a crossover with the Harry Potter world? The battle droids could be found in Hogwarts. They might be confused by the magic there and the students could try to figure out how to use their technology. And the droids would surely be a strange sight among the wizards and witches.
One idea could be a crossover between a classic superhero like Superman and a powerful anime character like Goku. Picture them in a battle where they have to adapt to each other's fighting styles. Another could be a crossover of characters from different horror universes, like Freddy Krueger and Pinhead, in a fight to the death in a nightmarish realm. And a third idea might be to cross a high - fantasy character like Gandalf with a modern - day action hero like John Wick. They could team up against a common enemy in a world that blends magic and modern weaponry.
One idea could be a story where Akira and Shiki are forced to team up against a new threat in the Togainu no Chi world. Maybe a powerful and mysterious figure emerges, and they have to put aside their differences to protect their territory.
Akira Kurusu in the 'My Hero Academia' universe is a really creative idea. Imagine him being in a world where quirks exist and how his Persona abilities would be seen. He could either be seen as a hero or a threat, depending on how the story unfolds. His Persona skills might be mistaken for a really powerful quirk, and he'd have to deal with the hero society's expectations and rules.
One idea could be exploring an alternate universe where the Battle Force 5 team has different powers or vehicles. For example, instead of their regular rides, they could have flying saucers with unique offensive capabilities.
Maybe a crossover with a magical anime. The nanbaka characters could suddenly find themselves in a world full of magic. Some of the nanbaka characters might be really good at using magic in unexpected ways, like Jyugo using his shackles in a magical battle.