Servant of Evil is from The Story of Evil (悪ノ物語 Aku no Monogatari), or more commonly known as the Servant of Evil series (悪ノ娘 Aku no Musume) which is a series of music videos using Yamaha's Vocaloid vocal synthesizer software. It is a collection of 9 songs that intertwine to create the story. They were all made by Mothy, also known as Akuno-P(悪ノp).
The first song of the series, "Daughter of Evil", did not gain much attention when it was uploaded to Nico Nico Douga on April 6, 2008. It was until a few weeks later when the second song of the series, "Servant of Evil (悪ノ召使 Aku no Meshitsukai)", was uploaded it did gain popularity among the Nico Nico Douga users.
"Servant of Evil sheet music or stave is also offered for you to download.