I love this cover so much omg???? The muffled piano really gives the song such an ethereal feel! Also I love seeing new vocaloid fans! For a few recommendations, check out Rolling Girl by wowaka and Tokyo Teddy Bear by Neru! They're classics :^)
If you look at the lyrics you see the song is about all the people around you giving up and giving in to their vices, letting themselves slip away into oblivion while they encourage you to do the same. This is the “Dance of the Corpses”