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.
A common theme is the slow - burn romance. Given Kurama's initial aloofness and Nanami's determination, their relationship often develops gradually in fanfiction. Another theme is Kurama's past affecting their relationship. His history can add depth and drama to their interactions.
In such a fanfiction, it could be that the pregnancy brings out a new side of Tomoe. He might become more domesticated, learning to cook special meals for Nanami. Nanami would be glowing with the pregnancy, and their relationship would be filled with new - found tenderness. Their friends in the spirit world and human world would also be involved. Mizuki might give Nanami some unique gifts for the baby, like a magical amulet for protection. Kurama could offer his wisdom on how to raise a child with powers. The whole story could be about how this pregnancy not only changes their lives but also the relationships they have with those around them.
Another interesting one could be 'Tomoe's Promise to Nanami'. In this story, Tomoe makes a solemn promise to Nanami, and the rest of the fic is about how he tries to keep it. It shows their loyalty and deep connection in a really touching way.
One great place to find kamisama kiss kurama x nanami fanfiction is on Archive of Our Own (AO3). There are many talented writers who create interesting stories about them. Some might focus on their budding relationship, while others could explore different scenarios like them going on adventures together.
You can start by looking on popular fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfictions, and you can use the search function to specifically look for Kamisama Kiss fanfictions related to Nanami and Tomoe.