User blog comment:B214/High School DxD EX/@comment-26890593-20150821161049/@comment-3965848-20150821203011

I'm pretty sure it's related to the main story, some guess they travel back in time right after Vol. 21, or to an earlier Volume but the main cast gets their memories wiped so they couldn't be able to mention the event.

I'm also sure the kids know very well their father is a huge pervert.

And Born along with the entire anime series really is a world separate from the main story.

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