On 25th Dec 2016 came the Special Edition of the 6th Manga Volume out (ISBN: 9784041046807). It includes the about 1 hour long Drama CD "Show Must Go On". It's on Niconico (until removal) for those who want to listen to it.
the drama cd track 1 is already up and translated in youtube but under unlisted. i havent finished listening to track 1 but its about the fake nazarick that aura is constructing and some misunderstanding about declaring independence