Well, Akeno Himejima is quite fascinating. She has a dual personality - sweet on the outside but with a bit of a sadistic side. Then there's Koneko Toujou, the small and cute yet powerful nekoshou. Her development from a cold - hearted fighter to someone more open is really engaging.
The main character is Issei Hyoudou. He's a high school student who gets turned into a devil. Then there's Rias Gremory, a powerful devil and the president of the Occult Research Club. Akeno Himejima is also important. She's a devil and one of Rias's servants.
In the 'Highschool DxD Light Novel', Issei Hyodo is the protagonist whose transformation into a devil sets the story in motion. Rias Gremory, with her alluring and powerful presence, is crucial. Akeno Himejima, who has a complex personality and a special relationship with Rias, is important. Koneko Toujou, a cute yet strong devil, and Asia Argento, a kind - hearted girl with a special power, are also among the main characters. Each character brings their own unique traits and backstories to the overall narrative of the novel.
In addition to Issei and Rias, Akeno Himejima is likely to be a main character in this volume too. She is one of Rias's peerage members and has a special relationship with Issei. And there are other characters like Koneko Toujou who play significant roles in the overall story arc of the series and would probably be important in volume 25 as well.
The unique power - up systems for the characters make them stand out. For example, Issei's Boosted Gear gives him various abilities as he levels up. Also, the fact that they are devils, angels, and other supernatural beings with their own hierarchies and rules is different.
Issei Hyoudou is a central character. He is a perverted but kind - hearted high school student who becomes a devil. He has a strong will to protect his friends and the ones he loves.
Ayanokoji Kiyotaka is quite interesting. He's a very intelligent and mysterious character who often hides his true abilities. Horikita Suzune is also interesting. She's ambitious and determined, but also has her own insecurities. And then there's Kushida Kikyo, who seems nice on the surface but has a more complex and somewhat devious side.
I think Asia is a character that can be really interesting when changed. If her healing powers were different, like if she could also resurrect the dead or had some sort of dark side to her healing. That would completely change her role in the story. Also, Sirzechs. If he was more of a villain in the fanfiction, it would turn the whole 'High School DxD' world upside down. His power and influence are so great that any change to his character would have a far - reaching impact. And Gasper. If he was more confident and less shy, and had different vampire abilities, that would be a really cool change to explore in fanfiction.
It's about a perverted high school boy named Issei Hyodo who gets killed on his first date. He is then reincarnated as a devil by a devil girl named Rias Gremory. The story follows his adventures in the supernatural world filled with devils, angels, and other mythical creatures as he tries to become stronger and build his own harem.
Well, in the series, there are often power - ups for the main character. Maybe in volume 25, Issei could gain a new ability or face a new and powerful enemy. It might also explore more of the complex relationships between the different factions. For example, the devils' internal politics and their relations with the angels. There could also be some romantic developments between Issei and the female characters around him.
The Highschool DxD light novel is not ongoing. It wrapped up some time ago, but its popularity still remains high among fans.