User blog comment:B214/High School DxD EX/@comment-25262334-20151125172134/@comment-27232228-20151125181924

The guys have already predicted several of these (based from the main LN, somehow a bit NSFW):

- Ravel took the Hyoudou surname like Asia and left her clan, since the Phoenix family have already arranged to let her stay in Issei's care "permanently" since Volume 11 (the real talks apparently takes off-screen, plus the love matter is already out of question).

- The mothers have big oppai, I think everybody already know that. Koneko already shown in her Shirone mode, Ravel and Asia were lampshaded by Issei himself that theirs were growing. The remaining girls are already this by default (Btw, Xenovia and Irina's are considered big by both Japanese and American standards (87 cm, and with the drawing provided, that's equal to 34D in American standard :D). As for Sona... no idea, but if we look at Serafall at the present, it is not that possible.

- The Nekomata Sisters gave birth at the same time is also already speculated. One even commented that Issei must have given one hell of a threesome :D