I recommend Blade of Vengeance. The plot of this book is as follows: The male protagonist has been a big boss since he was young and has never failed. But one day, his brother and woman betrayed him and made him lose everything. Thus, he began his path of revenge. He pulled himself together and finally succeeded in his revenge. I hope you like my recommendation.
Well, there's 'Giyuu and the Mysterious Female'. In this fanfiction, a female character with special powers enters Giyuu's life and they go on adventures together. Also, 'Female Friendship with Giyuu' focuses on the platonic relationship between a female and Giyuu, showing how they support each other in the demon - slaying world.
There's also 'Shinobu and Giyuu: A New Chapter'. This fanfic focuses on a post - main - story scenario where they team up for a special mission. It's really interesting as it shows their growth from their initial somewhat tense relationship to a more harmonious partnership.
In a Giyuu x Shinobu fanfic, the setting and plot can vary widely. Some might be set during the main events of the Demon Slayer universe, with them facing demons together. Others could be more of an alternate universe story, where they meet under different circumstances, like in a modern - day high school AU. The fanfic could also delve into their backstories and how those experiences shape their relationship. For instance, Shinobu's past with her sister could play a role in how she opens up to Giyuu, and vice versa for Giyuu's own traumas.
I would recommend 'Whispers of the Heart' for Giyuu x Shinobu fans. This fanfic focuses on their unspoken understanding. It's full of small moments that build up their relationship, like when Shinobu leaves a small flower on Giyuu's doorstep as a sign of her care. Also, 'Shadows and Sunlight' is worth checking out. It has a great plot that involves them having to go on a secret mission together and how that journey changes their relationship from colleagues to something more intimate.