The Highschool DxD manga has indeed finished. It wrapped up after completing all the planned story arcs and providing a satisfying conclusion for the readers.
The 'High School DxD' light novel offers a complex world - building. There are different factions like the devils' underworld with its own hierarchy and rules, the angels with their divine mission, and the fallen angels who have their own motives. This creates a lot of interesting conflicts and alliances. The battles are also exciting, with the use of different supernatural powers and the strategic thinking of the characters.
The 'High School DxD' light novel stands out because of its unique premise. Combining a high school setting with the supernatural world of devils, angels, and fallen angels is not something you see every day. It gives a fresh take on the typical high school story.
Well, the plot of Highschool DxD manga light novel is centered on the supernatural. Issei becomes a devil and gets involved with the devil society led by Rias. There are battles against other devils, as well as conflicts with angels and fallen angels. Each character has their own backstory and powers. For example, Rias has her own peerage which she uses in Rating Games to gain status. Issei's growth as a devil, both in terms of power and character, is a major part of the story. It's also full of comical moments, especially due to Issei's perverted nature which often gets him into trouble.
The Highschool DxD manga has gone a long way, presenting detailed plots and character developments. However, to know exactly how far it has gone, you might need to check the latest releases or related manga forums for the most up-to-date information.