The story mainly follows Issei Hyodo, a high school student who gets killed on his first date and is later resurrected as a devil. He then becomes part of the Occult Research Club at his school. There, he gets involved in various battles against other supernatural beings, all while trying to become stronger and also dealing with his new devilish desires and relationships with his female comrades.
Well, there are prequel novels that offer background on some of the characters and events. Also, there are companion novels that explore additional adventures and story arcs within the same world.
In a Naruto and High School DxD fanfiction, there could be a scenario where the protagonists of both stories meet in a neutral dimension. Issei from High School DxD might be intrigued by Naruto's ninja skills and determination. Naruto, in turn, could be curious about Issei's Sacred Gear. They could start training together, sharing their knowledge and skills, and ultimately have to face a common enemy that threatens both their worlds.
In a high school fanfiction, perhaps Itachi is a new transfer student. Sakura, being the curious and friendly girl she is, decides to befriend him. They end up getting paired for a school project. At first, Itachi is quiet and reserved, but as they work together, Sakura discovers his hidden depths and he starts to open up to her more. This could create a really interesting dynamic between them.
In a high school fanfiction, Sakura Haruno and Itachi could have an interesting relationship. Maybe Itachi is the mysterious senior that Sakura admires from afar. He could be the top student, both in academics and in some kind of martial arts or special skills. Sakura, on the other hand, is the determined girl trying to prove herself. Their paths might cross in the school library, where Itachi is often found reading advanced books and Sakura is there studying for her exams. Itachi might notice Sakura's hard - working nature and offer her some advice in a very subtle way.
There aren't many direct novels specifically tied to High School DxD Season 3. But some spin-off or companion novels might exist that expand on the story or characters.
It's about a story in a high school setting with elements of the supernatural. It involves characters with special powers and abilities, and their adventures and relationships within the school and the larger supernatural world.