A very large lossless (.ogg) collection of doujin [0] Touhou [1] music. Googling the name should have taken you to the website [2] which might provide a bit more information. It's split into three torrents: One for just the music (1.65TB in size), one for Album Scans (76.5GB in size), and another for extras like lyrics, bundled item scans, and other misc. extras (24.2GB in size).

Or in simple terms: A large collection of cover songs for the soundtracks of a popular Japanese bullet-hell game series.

[0] https://en.wikipedia.org/wiki/D%C5%8Djin

[1] https://en.wikipedia.org/wiki/Touhou_Project

[2] http://www.tlmc.eu/