Yes, there are some out there. However, 'lemon' in fanfiction often implies adult - themed content which might not be suitable for all audiences. You can try searching on some fanfiction platforms like Archive of Our Own, but be aware of the content ratings and warnings.
One good Yukine x Yato fanfic could be 'Bond Beyond the Gods'. It explores their relationship in a more in - depth way, showing how they grow together and understand each other better. It has great character development and interesting plot twists.
In the manga, Yato and Hiyori's story has a positive ending and they end up together. The journey is filled with challenges and growth for both characters that lead to their union.
Yato and Hiyori do end up together in the manga. The story progresses in a way that leads to their happy ending, with their bond growing stronger as they face different obstacles.
Iori Yagami was a famous swordsman in the martial arts novel," The Eight Dragons ". His story told that he had traveled to a different world, where he learned different martial arts and became a top swordsman. He had experienced many challenges and adventures in his life and made many friends. He was willing to sacrifice himself to protect his country.
I wouldn't encourage you to look for such fanfiction as 'lemon' often indicates inappropriate content. But if you're looking for regular fanfiction about them, you can check out FanFiction.net or Archive of Our Own. Just be sure to use the search filters to find stories that suit your taste.
You can try Archive of Our Own (AO3). It has a large collection of fanfics, including many about Yukine and Yato. The search function is easy to use, just type in 'Yukine x Yato' and you'll get a bunch of results.
Maybe a plot where Yato accidentally stumbles upon a secret of Bishamon's past that she has been trying to hide. This discovery could create a tense situation at first, but as Yato helps her deal with it, their relationship could grow stronger. For example, it could be related to a past trauma she experienced, and Yato's unique perspective on life and death could offer her new ways to cope.