Well, one possible plot could be that Tasuku and Kai initially have some sort of rivalry when they meet. Maybe they're competing in a card game. Aichi, being the kind - hearted one, tries to ease the tension between them. As the story progresses, they find out they have more in common than they thought and end up teaming up against a common enemy in the card game world.
The plot might involve Tasuku meeting Kai and Aichi in a new card shop that just opened. Kai is there to check out new cards and Tasuku is there to practice. Aichi comes in later. At first, Kai is a bit dismissive of Tasuku's skills. But Aichi encourages Tasuku to show what he can do. Eventually, they start sharing card strategies and form an unexpected friendship.
It could be Ren. Ren is often portrayed as a bit of a troublemaker in the card - playing universe. He might see Tasuku, Kai and Aichi as a threat to his own status as a top player and try to undermine them at every turn.
Yes, there are likely some fanfictions out there that might include a kiss between Kai and Aichi. You can try searching on popular fanfiction websites like Archive of Our Own or FanFiction.net.
One idea could be a story where Kai and Aichi go on a journey through a magical lemon grove. In this grove, they discover that the lemons have special powers that can heal the broken relationships in their world. Another could be a modern - day AU where they run a lemonade stand together and through that, they learn more about each other's dreams and fears.
One way is to show them outside of cardfights. Maybe they start hanging out more, like going to card shops together to look for new cards. They could talk about their lives, their dreams related to cardfighting. Also, if one of them gets into trouble, like Aichi being bullied by some other cardfighters, Kai could come to his rescue. This would strengthen their bond. Another aspect could be that they start training each other's decks, sharing their insights on different card combinations. Through these interactions, their relationship can grow in a more personal and friendly way.
There's a fanfic called 'Kai and Aichi: A New Adventure'. In this one, they embark on a journey to discover a new type of card that could change the world of Cardfight Vanguard. The story is filled with action, friendship, and a bit of mystery as they face various opponents and obstacles along the way.
Well, a good plot for their fanfiction could be that Kai has lost his confidence in his cardfighting skills after a major defeat. Aichi then steps in to help him regain his confidence. They train together, share their strategies, and in the process, their relationship deepens. Or perhaps they are both on a quest to find an ancient cardfighter who is said to hold the secrets to ultimate victory. Along the way, they face many challenges and their bond grows stronger.
One popular kai x aichi fanfiction might be those that explore their friendship evolving into a deeper emotional bond. For example, stories where they support each other through difficult cardfights and gradually realize their feelings for one another.
They could be friends having an intense argument in a story. For example, they might be arguing about a card game strategy, where their strong opinions clash but in the end they learn from each other.
As I said before, Archive of Our Own and FanFiction.net are good places to start. Just use their search functions and type in relevant keywords like 'Kai and Aichi' and 'kiss' to see if there are any stories that match.
Another option is to check out some Cardfight!! Vanguard fan communities on social media platforms like Reddit or Tumblr. Sometimes fans will share their own fanfictions or recommend good ones they've read. You can also post a request for kai x aichi fanfiction in these communities and see if anyone can point you in the right direction.