I'm not entirely sure as I haven't read it specifically. But generally, a web novel could be about various things like adventure, fantasy, or the coming - of - age story of the main character.
One unique feature could be its world - building. It likely creates a world that is distinct from our own, with its own rules, cultures, and species. This makes the story very immersive.
Light novels usually have a variety of themes. 'naze boku no sekai wo daremo' might be about a protagonist who feels isolated in their world, as the title could be loosely translated to 'Why is no one in my world?'. It could explore themes of loneliness, the search for connection, and perhaps the character's journey to change their situation.
One light novel that might be similar is 'Sword Art Online'. It also has a complex world - building aspect like 'naze boku no sekai light novel'. Another could be 'Re:Zero − Starting Life in Another World'. It has a unique story with the protagonist facing various challenges in a different world, just like in 'naze boku no sekai light novel'.
A sekai visual novel is a form of literature - meets - gaming experience. It is often presented in a visual format with character sprites and scenic backgrounds. These novels can have deep and complex storylines. They may also include elements of character development, relationship building, and plot twists. In a sekai visual novel, you as the player are an active part of the story, and your choices can lead to different endings, which adds to the replayability factor.
Since I haven't read 'boku girl boku no arbeit novel' directly, I can only speculate. However, from the title, it might deal with the concept of identity ('boku girl' could imply something about gender identity or self - perception). Also, 'arbeit' might suggest themes related to work or purpose in life. There could also be themes of personal growth and the challenges one faces in the context of work and self - identity.
The 'kyoukai no nai sekai' full story might revolve around characters who find themselves in a world without the usual limitations. This could lead to unique challenges and opportunities for them. They might have to re - evaluate their values and ways of life. For example, if it's a world without social boundaries, they could face issues related to identity and community. Maybe the story is about how they adapt or try to create new boundaries in this strange world.