We can expect more exciting adventures of the characters. There might be new power-ups, more intense battles, and deeper exploration of the relationships between the characters.
I don't think it's a good idea for a newcomer to start with Volume 23. It's better to start from the beginning to understand the characters, the world - building, and the basic plotlines.
I'm not sure specifically as I haven't read Volume 23 yet. But generally, in the High School DxD series, we can expect more development of the characters, new supernatural elements, and exciting battles between different factions.
The 'High School DxD' light novel is about a high - schooler named Issei. After his death, he's reborn as a devil. It has a lot of elements such as battles between different factions like devils, angels, and fallen angels. There's also a focus on Issei's growth in power and his relationships, especially his romantic interests which are quite numerous as he interacts with different female characters from different species in this supernatural setting.
It's a story mainly set in a high school with a supernatural twist. It involves characters like Issei Hyodo, who gets involved in the world of devils, angels and fallen angels. There are battles, a bit of romance, and lots of action as Issei tries to become stronger and deal with the various power struggles among the different factions.
It's about a high school student named Issei Hyodo. He gets killed on his first date and is then reincarnated as a devil. He has to deal with the devil society, its politics, and also various supernatural threats. There are a lot of action scenes, character development, and some harem elements as he forms relationships with different female characters.
The 'High School DxD' light novel is about Issei Hyoudou, a perverted high school student who gets killed on his first date. He is then revived as a devil and becomes a servant to Rias Gremory. The story involves his adventures in the supernatural world, battles against other devils, fallen angels and various mythological creatures, as well as his growth in power and his relationships with the female characters around him.