User blog comment:SpookyBoogie27/Light Novel Spoilers/@comment-1359322-20141207104448

Finally brought myself to check Ishibumi's blog. So a minor bit of updates.

For the future volumes, Ishibumi will continue his plan on making another volume for the main four (Rias, Asia, Akeno and Koneko). Ishibumi also mentioned he'll be expending a bit more on the secondary and tertiary heroines like Le Fay, Kuroka and Kunou. Order is undecided yet, but it'll be main girls > other girls.

Ishibumi also mentioned about hyping the new Occult Research Club and new Student Council. I'm guessing we'll have new characters to write about now. ( ._.)

Anyway some speculation, since Ishibumi said he didn't really touched on the Youkai in Volume 9, we can expect that either the Koneko, Kuroka or Kunou volume would focus on the Youkai.