One idea could be a beach volleyball tournament where the characters from Haikyuu and Free come together. The Haikyuu players' skills in teamwork and strategy could blend with the Free characters' swimming abilities as they adapt to the new sport. Another could be a training camp where they all learn from each other's athletic disciplines.
I really liked 'Haikyuu at Chaldea'. In this fanfiction, the Haikyuu characters end up in the FGO world. The author does a great job of showing how the Haikyuu team members adapt to the strange new environment filled with magic and Servants. They bring their own team spirit and determination, which has an impact on the events in the FGO world.
Hinata and Haru would be an interesting pairing. Hinata's energetic and determined nature could contrast with Haru's more laid - back but equally passionate about swimming attitude. They could learn a lot from each other, like Hinata learning about the calm focus from Haru and Haru getting inspired by Hinata's unwavering drive.
One idea could be a Haikyuu and My Hero Academia crossover. The volleyball players could suddenly discover they have quirks. For example, Hinata might have a quirk that makes him jump even higher, like a super - powered leg spring. It would add a whole new dynamic to their games and rivalries.
You should also focus on the characters. Figure out how they would react to the new elements from the other fandom. In a Haikyuu and One Piece crossover, the volleyball players might be amazed by the Devil Fruits and the strange powers they give. And Luffy might be interested in their intense volleyball matches. Write down all these ideas before starting to write the actual story.
The appeal lies in the contrast of the two universes. FGO has a complex, magical world full of powerful Servants, while Haikyuu is all about high - energy volleyball and the spirit of a team. When combined, it creates a really unique and interesting dynamic. For example, seeing a Servant from FGO trying to understand the rules of volleyball in a Haikyuu - style court is both funny and engaging.
One great 'Haikyuu! Bnha Crossover Fanfic' is 'Volleyball Heroes'. It combines the unique powers from Bnha with the exciting volleyball matches of Haikyuu. The characters' interactions are really interesting, like when Midoriya tries to learn volleyball techniques from Hinata. It's a fresh take on both universes.
First, you need to be familiar with both universes. Know the characters, their personalities, and the rules of each world. For example, in Haikyuu, understand the volleyball strategies and the different teams. In Bnha, know the quirks and how they work. Then, think of an interesting concept for the crossover. Maybe it could be about the Bnha characters joining a volleyball tournament in the Haikyuu world.
In a Haikyuu fanfic featuring Sakura Haruno, it could be really interesting. Maybe she could be a manager for one of the volleyball teams, bringing her own unique skills from the Naruto universe like her medical knowledge to help with the team's injuries. It would add a whole new dynamic to the story.
A plot could revolve around a time - travel situation. Some of the characters from Kuroko no Basket are sent to the world of Haikyuu and vice versa. The basketball players are suddenly thrust into the world of volleyball and have to adapt quickly. They end up forming a combined team with the volleyball players to compete in a special event that is designed to test the limits of their skills and teamwork.