A great crossover could involve the sharing of powers. For example, a character from Naruto might gain some yokai - like abilities from the Nura world and vice versa. This could lead to some really cool fight scenes and character development. Maybe Naruto himself could learn some yokai magic and use it in his battles, creating a whole new fighting style.
One interesting plot idea could be a crossover where Naruto characters end up in the Nura world. They could team up with the Nura clan to fight a common enemy that threatens both their realms. For example, an ancient evil that can manipulate chakra and yokai energy.
One idea could be exploring the backstory of some minor yokai characters in more detail. For example, you could write about how a certain yokai came to be part of the Nura Clan.
Rikuo Nura is a great character to write about. His dual nature as a human during the day and a yokai leader at night provides a lot of room for character development. You can explore his struggles to balance these two identities and how he deals with the expectations of both the human and yokai worlds.
The complex hierarchy within the yokai clans can be a great aspect to explore. You could write about power struggles, alliances, and betrayals among different levels of yokai. For instance, a lower - ranked yokai trying to rise in the ranks by outsmarting the higher - ups.
Kurotabo is quite an underrated character. He is very loyal to the Nura Clan and has his own set of skills. Fanfiction could focus on his past and how he developed his loyalty to the Nura family.
For a crossover with a mecha anime, Kubinashi could be a key character. His skeletal form and his skills could be used in piloting or modifying mechas. And for a crossover with a ghost - hunting series, Nurarihyon, with his vast experience and power, could lead the team in dealing with both yokai and other supernatural entities.
A crossover with a time - traveling story could be cool. The Nura clan members get sent to different time periods and have to find a way back while also making sure that their actions in the past or future don't disrupt the balance between the human and yokai realms.
Rikuo Nura from Nura Rise of the Yokai Clan has a strong claim. He is the leader of the Nura clan and has both yokai and human forms. His yokai powers are vast, and if he were to gain some ninja skills from the Naruto universe, he could be nearly unstoppable. He has the ability to command a large number of yokai, which is a great asset in any battle.
One great fanfiction could be about the yokai clans coming together to face a common threat not shown in the original series. It might focus on the relationships between different yokai characters and how they overcome their differences to fight for the safety of their world.
One possible plot could be that Harry Potter somehow gets transported to the world of the Nura Clan. He might initially be confused by the yokai and their ways. But with his magical skills, he could help the Nura Clan in their battles against other dark forces. For example, he could use his Patronus to fend off some particularly menacing yokai threats.