Oddly from nintendo youtuber, Nathanial Bandy. He did a video of Mario 64 rom hacks (I think it was slide rom hacks), and night of nights was the theme for one. Me, knowing nothing about touhou, said "what the heck is this music and why is it so fast?". I then saw a comment saying the name of the song, searched it, and the rabbit hole opened there. I watched loads of videos on it until one day I said to myself, "why don't I play a Touhou game?", searched on youtube for "how to download touhou", found the website, and thats pretty much it.