User blog comment:Jopjopjop/High School DxD BorN episode 3 review/@comment-149.88.55.35-20150418204414/@comment-26209278-20150418220445

Think they'll keep the order of the major events as the LN, so Sona RG, then JD, then Loki battle, I think.

All i know for certain is that they're mixing the 1st half of #7 into the 5/6 stories, then leaving all the important halfs of the 3 books in the 2nd half of the season, such as the RG, the Diodora fight/JD and the Loki fight.