Blue Exorcist Vol. 13 (manga)

The Exwires learn the tragic story of what happened to Izumo's mother, Tamamo, when the Illuminati's mad Professor Gedoin sought her out in order to conduct his insane experiments. Now Izumo has been captured and is next on the Professor's list of test subjects. Rin, Yukio, Shiemi, Suguro and Konekomaru head deep into Dream Town Inari to rescue Izumo, but what they find there is a horror none of them ever expected...