User blog comment:B214/High School DxD EX/@comment-117.195.118.24-20150629125656/@comment-16281343-20150629194749

When Season 2's novel came out one September 2013, the current Volume published is Volume 15 and only a month before Volume 16.

The story on that novel took place after the Season 2 anime.

It won't be a surprise if EX takes place after the anime as well.