Song: Demoniac
Instrument: Church organ
Anime: Shingetsutan Tsukihime
Artist: Toshiyuki Ōmori
Album: Shingetsutan Tsukihime OST 1
Comments: It's only instrumental with a single instrument (church organ).

Here is the song on youtube:

http://www.youtube.com/watch?v=-G-uiuFSNdY

Thank you very much for your help.

Check for a PM. :)