Their response is here: https://forums.sekaiproject.com/forum/community/news-and-announcements/362-april-2016-q-a-livestream/page2 - In short, it implies the licensor doesn't want to, so they need pressure from their userbase. They specifcally issued a call to arms for posts in their forum.
So I posted onto their forum, in this thread here: https://forums.sekaiproject.com/forum/main-forum/41-questions-about-the-availability-of-things-in-devil-on-g-string/page2
I'd also post this in the MangaGamer forums ... if such a thing existed.