Sometimes people ask me how to find music in my particular specialty -- how to wade through the vast quantity available and cut it down to something more manageable.
There aren't any good answers, really. Even now, I think that I'm probably overlooking some huge number of bands that I'd really enjoy. But what I do is pretty simple:
YouTube spidering. Honestly, I just pick a song and start clicking related videos.
Now, YouTube's algorithm for relatedness seems to give me 3 categories: base track, arranging circle, or uploader. Usually, if I'm looking for something new, I'll focus on the first one. It's entirely possible to spend hours clicking through to different "Lullaby of Deserted Hell" arranges, for example. (And that's not even one of the more popular songs.)
And that brings up a possible refinement. This wouldn't have been possible back when the maximum video length was ten minutes, but now there are 3-hour-long medleys of particular themes. You can just start from one of those, mark down circles you like, and then spider.
And once you've done that for a while, built up some circles you like, then you can start tracking down the member connections. Go to vgmdb and click on an arranger's or vocalist's name. The odds are they've worked with more than one circle
. Go listen to some of their stuff with other circles. Continue spidering along those lines for a while.
This should keep you busy for a few years. And then, eventually, it starts to blur and you have to go back and listen to it again to find tracks that you've heard once and never been able to track down since.
Incidentally, if anyone knows who did that Touhou x Utena arrange album, I'd be really curious to hear it again.