So now that I have time, here's more information about this series.
It's based on Mesopotamian mythology, and specifically on the religion of Sumer. For reference that's one of the earliest known civilizations, older than 4000 BC. The best known myth from that era is the story of Gilgamesh, but that's not what this story is about. The title, Duranki, refers to "E-dur-an-ki", a temple for the god Enlil that once stood in the city of Nippur. The name "E-dur-an-ki" means "House of the link between heaven and earth."
Courtesy of @puella, The little blurb on the promotional page says:
Ah, so Duranki is the then-unnamed project that Miura alluded to in that French magazine interview earlier this year? It's kinda strange though, because I imagined that project to be something by him personally (a sequel to Gigantomachia, for example) rather than by Studio Gaga.
The word "interstice" here is the same one used in Berserk, with the same meaning.
Still, fans should not expect Duranki to be set in the same fictional universe as Berserk. Just sayin', in case people start giving too much thought to the word "interstice"
And for the guy who was curious, in volume 40, Miura's staff is listed as being Yoshihiro Kurosaki, Akio Miyaji, Nobuhiro Hirai, Naohide Nagashima. I expect these people are involved here, but we won't know for sure until YA details it.
If you ever get to write another letter to Miura, you should ask him whether he intends for Studio Gaga to become a brand-name mangaka collective like Clamp or whether he envisions it as an "incubator" for discovering, creating and breaking in the next generation of young manga artists. If Duranki becomes successful, you can reasonably imagine at least one of the above mentioned people becoming the next household name mangaka in the future.