User blog comment:B214/High School DxD EX/@comment-26890593-20150821161049/@comment-3965848-20150821214622

@Gary The whole anime even BorN is an adaption of the LN and if BorN is and AU then so is the entire anime since its canon to BorN, it even shows flashbacks to the previous seasons. So yes the entire anime series is in fact a separate universe from the LN

I'd also say the manga counts a universe separate from the LN and anime.