Sure. 'Vampire Hunter D' by Hideyuki Kikuchi is a great start. It introduces the world of D, a half - vampire, half - human hunter. Another one could be 'Raiser of Gales' which continues the adventures and expands on the lore of the series.
A fanfiction might focus on Doris' relationship with the people in her village. It could show how her life was before D's arrival, her daily routines, and how she was seen by the villagers. For example, perhaps she was a bit of an outcast because of her family's past, and this could add more depth to her character.
The number of Vampire Hunter D novels varies depending on different editions and releases. Generally, there are around a dozen or so. However, this can change over time with new additions to the series.
I'm not entirely sure as I haven't read it in detail. But generally, it might be about a vampire hunter named D and a character named Leila. It could involve their adventures in a world full of vampires, perhaps battles against the undead, and their own personal stories and growth within that dangerous environment.
For some readers, it could be a bit challenging as it has a unique world - building with its own set of rules regarding vampires, dhampirs (half - vampires like D), and the post - apocalyptic setting. However, if you take your time to understand these elements as you read, it becomes easier. The story also has a lot of action and adventure, which can help keep you engaged even if you are a bit confused at times.
Since it's part of the 'Vampire Hunter D' series, volume 7 novel would likely follow D's ongoing battle against vampires. It could explore more of D's past or his unique abilities. There might be new challenges for D, like a powerful vampire lord that he has to defeat. The story could also introduce new elements to the world - building, such as different types of vampire powers or new regions that D travels to. And it might also show how D's actions affect the relationship between humans and vampires in that world.