Friendship is a common theme. Their bond and how they interact as friends are often explored. Another could be school - related experiences, since they are schoolgirls in the Yuru Yuri universe.
I'm not sure of specific fanfictions for Yuru Yuri's Yui x Kyoko. You can try searching on fanfiction platforms like Archive of Our Own. There might be various works there that explore their relationship in different ways, from cute friendship stories to more in - depth character - study - like fics.
For Kyoko, she could be shown as more vulnerable in the fanfiction. Maybe she has a fear of heights and Yui helps her overcome it, which shows her growth. Yui, on the other hand, could be developed by showing her more impatient side when things don't go as planned during an event at school, and Kyoko is the one to calm her down.
One interesting plot idea could be Kyoko and Yui getting lost together during a school trip. They have to rely on each other to find their way back, and during this time, they discover new things about each other and their friendship deepens.
One great fanfic could be about Himawari and Sakurako going on a school adventure together. Maybe they are paired up for a project and during the process, they discover new things about each other. For example, they find out they both have a secret love for a certain type of music. This could lead to them bonding over it and becoming even closer friends.
Anime specialty stores sometimes also sell light novels. You could check out stores in your area or search for ones that ship to your location. They might have the Yuru Yuri light novel in stock or be able to order it for you.
There are also some second - hand book markets, either online or physical. You might be able to get a used copy of the Yuru Yuri light novel at a relatively lower price there. However, make sure the source is legal and reliable.
The settings in the 'yuru yuri' world are often really charming. When it comes to Kyoko x Ayano fanfics, the school environment and the girls' interactions within it, like in the club activities, add a lot of flavor. For example, in some fanfics, their different ways of approaching club tasks lead to both comical and heartwarming situations that make the fanfics interesting.
One popular 'yuru yuri kyoko x ayano fanfic' is 'A Day in Their World'. It beautifully captures the friendship between Kyoko and Ayano with some sweet and funny moments.
One popular story might be about their adventures in school together. It could show how they support each other during club activities, like when they are preparing for a school festival. Their friendship grows stronger as they face various challenges.