One idea could be a story where they go on an adventure together to save their world from a dark magic. They face many challenges and in the process, their relationship deepens.
You can start by writing down some character sketches of both Kamisama Kirihito and Nanami. Consider their personalities, their strengths and weaknesses. This will help you write their actions and dialogues more accurately. For example, if Nanami is known for her kindness, show that in how she interacts with others in your story. Then, start with a scene that grabs the reader's attention, like a mysterious event that involves both of them.
Adventure could also be a theme. They could be on a journey together, facing various challenges and obstacles, and relying on each other to get through. This can create exciting and engaging stories as they explore new places and situations.
I'm not sure exactly which kirihito x nanami fanfic to recommend as there are many out there. You could try searching on fanfic websites like Archive of Our Own. They have a large collection of fan - created stories and you might be able to find some great kirihito x nanami ones by using their search function.
A possible plot could be that Nanami gets into trouble with a powerful spirit and Tomoe has to make a great sacrifice to save her. This sacrifice could be something like giving up a part of his power or his memories. It would show the depth of his love for her.
The main reason is their dynamic relationship. Tomoe is a powerful fox spirit and Nanami is a human turned god. Their differences create an interesting chemistry. It's like a classic 'opposites attract' situation.
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.
I really like the fanfic 'Tomoe and Nanami: Unspoken Promises'. It focuses on the more subtle moments between them. There are many sweet scenes where Tomoe shows his protectiveness over Nanami in his own unique way. It's a relatively short but very engaging read.
One possible scenario in such a fanfiction could be Nanami and Tomoe going on a journey to the spirit world together. They might face various challenges there, like dealing with mischievous spirits. Tomoe, with his powerful yokai abilities, would protect Nanami throughout the adventure. And Nanami, with her kind heart, could end up making friends with some of the spirits they encounter.
In a Tomoe x Nanami fanfiction, it would be interesting to write about a situation where they have to pretend to be a married couple for some spirit - world related reason. They would have to deal with all the implications of that, like sharing living quarters and acting affectionate in public. This would force them to confront their true feelings for each other.