User blog comment:B214/High School DxD Born Final Episode Review/@comment-124.82.58.141-20151210113305/@comment-15929029-20151210115224

At some point I have to agree with you, but it still has  some plot from the ln that was adapted in the anime version of dxd. This is the problem, there are many reasons why the anime was being mixed-up.

First, the anime budget is very small for a small animation company that the limit was only 12 episodes for a 3-5 volumes..

Second, they are making other anime aside from dxd, they are busy..

Third, because of what they did (they only limit the episode to 12), they mixed-up big time that 3-5 volumes on the 2nd half of the season and change scenes on the last 2-3 episodes I guess which makes the anime-only watcher to be you know, have the feeling of  unsatisfaction because they feel that something is missing and left them with a question of  "How" and "where".