Strike the Blood, Vol. 5 (light novel) : Fiesta for the Observers

Aya Tokoyogi and six other hardened magical criminals have broken out from imprisonment. Their goal--to completely erase the 'Witch of the Void,' Netsuke Minamaya, from existence. How these events will unfold in the Demon District will depend on the actions of the strongest vampire to ever exist, Kojou Akatsuki.