I know for a fact the reason who always
Works with Mamoru Oshii made the
Score but I don't think a real soundtrack exsists

The person who did the music for The Dark Myth is that Kenji Kawai
Person who always works with Mamoru Oshii so that makes
Me think that there must be a soundtrack but I have never
Seen one. I made a RANT about THE DARK MYTH on Alien Rap God (http://WWW.MAKINGARTWITHPROTEUS.COM)

There was no soundtrack release. I did even knew about this, being a Kenji Kawai fan.

Yeah that person did the music for The Dark Myth but there was no soundtrack.