Well, without having read the 'gakkou no kaidan light novel', it's hard to give a detailed account. However, light novels usually blend different genres. It could be a horror - themed story set in a school around the stairs. There might be a group of students who discover something strange about the stairs, like a hidden passage or a ghostly presence, and the story could revolve around their attempts to figure out what's going on and deal with the consequences.
You might be able to find it at some specialized bookstores that carry a wide range of light novels. Also, online platforms like Amazon could potentially have it, either in physical or e - book format.
I'm not entirely sure as I haven't read it specifically. But generally, a light novel often features a unique story. It might be about the events and relationships within a school for young ladies ('ojousama gakkou') from the perspective of the main character ('ore').
The 'Kamisama no Memochou' light novel mainly follows the story of the main characters' adventures in a unique world. They often get involved in various mysteries and challenges.
One great fanfiction idea could be that Nanami and Tomoe go on a journey to the spirit world to solve a mystery that threatens the human world. Along the way, they face various challenges that test their relationship and their individual powers.
One reason could be that its distribution was limited. Another possibility is that there aren't many reprints, making it scarce. Also, it might be more popular in certain regions and less accessible elsewhere.
I think fanfics that involve time - travel in the 'Kamisama Hajimemashita' universe can be really exciting. For instance, if a character travels back in time to change an important event in the story. Also, those that explore the mythology and lore of the series in more depth through creative plots are worth reading. Some fanfics might even introduce new supernatural elements that fit well with the existing 'Kamisama Hajimemashita' world.