User blog comment:B214/Volume 17 spoilers./@comment-16281343-20140220010926

{Quote|Next volume will be Irina main volume. Belial will most likely get involved since he has concerns something that took place in Ise's town and Irina+her parents has something to do with it.}}

Speculation : I see some revenge thingy here. The Devil that previously resides in the town before Rias is related to Belial, and that Devil was exterminated by Irina's Parents.