Sure, the Noragami manga is completed. It was a great ride with an ending that wrapped up the plot nicely. If you haven't read it yet, it's worth giving a go.
The theme of self - discovery is also quite popular. As he travels around, Kazuha learns more about himself, his powers, and his place in the world. For example, in some fanfics, he discovers new aspects of his wind - related abilities.
A really popular Heiji and Kazuha fanfiction is 'Under the Cherry Blossoms'. In this story, the setting of the cherry blossoms adds a romantic touch to their relationship. The author does a wonderful job of portraying their feelings through their dialogues and actions. For example, there's a scene where Heiji gives Kazuha a small token under the cherry tree, which symbolizes his deep love for her. There are also some really cute fanfictions that focus on their comical moments together, like 'Heiji and Kazuha's Hilarious Adventures' where they get into all sorts of funny situations.
Sure does. The story quest for Kazuha is quite interesting and reveals more about his journey and motivations. It adds depth to his character in the game.