Somewhere I found a post written by Kiuchi Hidenobu, a voice actor of Hei. It's from his personal blog and the date of posting is 24th November.
Spoiler:
It's finished.*
...Suou...
Everything is in her head.
* Judging from his other posts, it means the recording of the final episode is finished.
Source:
http://bee-nice.jugem.jp