Perhaps there's a prophecy in the wizarding world that mentions a being with both magical and ghoul - like powers being the key to defeating a new dark threat. The wizarding world thinks it's about a wizard - born with some strange mutation, but it turns out to be a half - ghoul half - wizard. Harry Potter and Ken Kaneki both get wind of this prophecy and team up to face this new danger together, learning from each other's worlds along the way.
A plot might involve a magical accident that transports some of the Tokyo Ghoul characters into the wizarding world. Kaneki could end up at Hogwarts and be sorted into a house. He'd struggle to hide his ghoul identity while also trying to find a way back home. At the same time, the wizards are intrigued by his unique abilities and some, like the more power - hungry ones, might try to use him for their own gain. Harry Potter and his friends would then have to decide whether to trust Kaneki or not.
Well, in a Tokyo Ghoul and Harry Potter crossover fanfiction, there could be a character who is both a ghoul and a wizard. This character would have to struggle with the dual nature of their existence. On one hand, they have the magic of the wizarding world, but on the other, they have the hunger for human flesh as a ghoul. They might use magic to try and control their ghoul instincts, like using a spell to suppress the urge to attack people.
One possible plot could be that Uta, with his unique mask - making skills from Tokyo Ghoul, gets involved in a situation where he has to create a special mask for a character from the Uta no Prince - sama world. Maybe this mask gives the Uta no Prince - sama character some special powers related to the ghoul world, like enhanced hearing or the ability to see in the dark. And then they have to navigate through both the music - filled world of Uta no Prince - sama and the dangerous world of Tokyo Ghoul together.
One possible plot could be that Naruto and his friends are sent to the Tokyo Ghoul universe by some sort of space - time jutsu gone wrong. Naruto, with his strong sense of justice, would be immediately intrigued by the situation of the ghouls. He might try to find a way to co - exist between humans and ghouls, using his ninja way. He could team up with some of the more sympathetic ghouls, like Kaneki, and together they fight against the more extreme elements on both sides, whether it's the violent ghouls who only see humans as food or the humans who want to exterminate all ghouls without question.
The plot could involve a shared threat that forces the Tokyo Ghoul and Parasyte universes to collide. Maybe a new type of organism emerges that is even more dangerous than ghouls or parasites. The characters would then have to combine their unique abilities to combat this threat. For instance, Kaneki's kagune and Shinichi's enhanced physical abilities with his parasite Migi could be used in tandem. This would create an interesting dynamic as they try to figure out how to work together while also dealing with their own internal struggles related to their inhuman natures.
One way the worlds could collide is through a magical accident. Maybe a spell in the Harry Potter universe goes wrong and opens a portal to the Tokyo Ghoul world. The wizards could be shocked to see the ghouls with their kagunes. And the ghouls would be equally surprised by the magic of the wizards.
The storyline could be really interesting. Maybe the ghouls could be a new kind of dark creature in the Harry Potter world. The characters from Tokyo Ghoul, like Ken Kaneki, might attend Hogwarts. He could struggle with his ghoul nature while trying to fit in with the wizards and witches. The magic in the Harry Potter universe could also have an impact on the ghouls' abilities, perhaps suppressing or enhancing them.
It could be really interesting. Maybe the wizards in Harry Potter world have to face the ghouls from Tokyo Ghoul. The magic spells could be used to fight against the kagune of the ghouls. For example, the Stunning Spell might stun a ghoul temporarily, giving the wizard a chance to escape or attack further.
The most interesting element is the power combination. For example, seeing a wizard from Harry Potter use magic against the ghouls in Tokyo Ghoul's world is exciting. Magic like spells and potions could have very different effects in the ghoul - filled Tokyo.
One plot idea could be that a character from Tokyo Ghoul ends up in Ikebukuro (the setting of Durarara). For example, Kaneki could find himself in the middle of the Dollars' activities. He might initially be confused by the different kind of chaos compared to the ghoul world. Another idea is that Celty's head mystery somehow gets intertwined with the ghouls' existence. Maybe there's a ghoul who has knowledge about her head, and this leads to an alliance between Celty and some of the Tokyo Ghoul characters to find out the truth. A third plot could involve the gangs in Durarara getting involved with the ghoul - human conflict in Tokyo Ghoul. They might try to take advantage of the situation for their own gains, but end up getting more than they bargained for as they learn about the true nature of ghouls.
The characters would interact in very unique ways. For example, Harry Potter might be initially cautious around the ghouls from Tokyo Ghoul. He's used to dealing with Voldemort and his Death Eaters, but ghouls are a completely different type of threat. Ken Kaneki, being a half - ghoul, could teach the wizards about the nature of ghouls, and in return, the wizards could show him some amazing magic spells.