Volume 7 coming on 10th of June.Edit
Yep, here we are, this is a *music* opening for a *text* novel known as HakoMari. It was presented at M3 whatsoever-fair at the cost of 400 yen. There also is an ED to the novel, but, Mikage Eiji did not upload it to his nnd-channel. The credits and additional info, including vol. 7 release dade goes below.
Here's rough transtation of the original message. "Hi, this is Mikage Eiji. We made our very own OST using our very own stuff. That feels awesome.
The seventh volume of HakoMari will be released at 10th of June, while now I'm recollecting contents of previous books.
Lyrics: Mikage Eiji
(Twitter @mikage_eiji) (blog http://agrank.blog.fc2.com/)
Music: Fujimiya Kei