I get a locked idle loop with a black background on starting a new game. Tried 3 different downloads, all 3 do this, but the dlsite trial doesn't. Has anyone managed to get this to work?

Same for me

Well, it works for me. You might have to install updated GPU driver, directx, .NET framework and certain versions of C++ if you haven't already.

not works

Figured it out. Turns out it has to be run with japanese locale, which can't really be done with a 64bit exe unless you actually change the locale of your system. Take a look at this: https://superuser.com/questions/905522/how-to-launch-a-64-bit-program-with-a-different-locale-than-the-system-locale