Thread:Sapphirrre/@comment-16281343-20150210201821/@comment-16281343-20150210203223

Are you asking why there are many characters that weren't introduced in the anime episodes?

Well, that's because High School DxD is Light Novel series that currently has 19 Volumes and because of its popularity had an anime adaptation.

The anime seasons 1 and 2 are Volumes 1-4 with the next season most likely animating Volumes 5 and 6.