Yes, there might be. You can try searching on fanfic platforms like Archive of Our Own or FanFiction.net. Sometimes these types of crossovers are created by fans who are interested in both gj bu kirara and kyoya.
You can try searching on Tumblr as well. There are many fanfic writers and readers on Tumblr. Some might post or reblog gj bu kirara x kyoya fanfics. Additionally, Reddit has some subreddits dedicated to fanfiction. You could post a request there asking if anyone knows of such a fanfic. Just be sure to follow the subreddit rules when posting.
Since there's not much information given, it's hard to say exactly. It might be a crossover fanfic if Kirara and Kyoro are from different sources. 'gj bu' could be an abbreviation related to the overall theme, like a group name or a special place in the fan - created universe. Maybe it's a story exploring their relationship, whether it's friendship, rivalry or something else.
One possible plot could be that Kirara and Kyoro are on a quest together in a magical world. 'gj bu' could be the name of the magical land they are in. They face various challenges and their relationship grows stronger as they overcome them.
Since I don't have much information on 'gj bu light novel', it's hard to say exactly. However, light novels usually have a distinct writing style that's easy to read. It might tell a story of a group of people in a special setting. For example, it could be about students in a magic school who discover their powers and deal with the politics within the school, or it could be about young adventurers exploring an unknown land and facing the perils there, but this is all just speculation.
You might be able to find 'gj bu light novel' at some specialized bookstores that carry a wide range of light novels. Some large chain bookstores may also have it.
One great Tamaki x Kyoya yaoi fanfic is 'The Bond Between Them'. It beautifully explores their relationship in a way that stays true to their characters. The story focuses on how they support each other through the challenges in their lives, with some really touching moments.
A Tamaki x Kyoya lemon fanfic would likely center around the relationship between Tamaki and Kyoya. Given the 'lemon' tag, it may contain scenes that are more sexually charged. It could start with the two characters having some sort of unspoken attraction to each other. As the story progresses, it might show how they navigate their feelings in a more private and perhaps more physical way. It could also delve into their insecurities and how they overcome them in the context of their relationship, all while exploring their relationship through the lens of the 'lemon' genre which often includes adult - themed elements.
One common theme is friendship evolving into something more. In many fanfics, they start as friends or clubmates and gradually realize their deeper feelings. Another theme is the exploration of their different social standings. Kyoya is often seen as more calculating and from a wealthy family, while Tamaki is more carefree and has his own charm, and how they bridge that gap. Also, the theme of self - discovery is present as they learn more about themselves through their relationship with each other.
A lot of Tamaki x Kyoya fanfics deal with the idea of mutual understanding. They have different personalities, and the fics often focus on how they come to truly understand each other on a deeper level. There are also fics that center around the challenges they face as a couple in the context of the world they live in, like dealing with family expectations or social status differences.