Japanese music indeed. Comes from a one-man game series precisely called "Touhou Project" (the guy makes the programming, music, story, art... well, the "art" is a special story). Wikipedia has more info.
It is also reputed to have some of the best game music ever for the simple fact that the music exceeds the games and is really good on its own (the guy releases solo albums that follow a storyline and sometimes feature tracks from the games but with improved quality or additional passages/sections)
It also has ridiculous, obscene, amounts of arrangements, remixes and rearrangements of all the genres you can imagine. However, a good amount of 'em are either techno/electronic stuff or vocals and pop or just plain weird. But there are solo violin, solo piano, "folkish"/Enya-like, orchestral and even plain good ol' heavy metal too. Oh, and even albums that joke about Final Fantasy (Advent-Cirno series)
With 10 games out and several "related" titles... there is plenty of musical material to listen to.
Some hate the original songs due to an excess of e-trumpets or the "cheap" synth feeling but... I love the chiptune feeling.
I usually see these games as playable music CDs (of course I'm over exaggerating) but that's how nice the musical experience can get. The series wouldn't be that interesting without the music backing it up.
177.6gb... my disk has 160gb. Good lord that's way too much.
A little warning: once you enter this terrain, well, obsession is just around the corner.