Fff I found out it's actually older than about 3 weeks, I think, but orz;; I just now saw it in the Rans xD;;; FF.
BUT THIS SONG I LOVE IT.
I don't know if I should keep canon elements when figuring out the story from Aku no Musume, since only a /few/ things are kept in this story. Like Miku is a Peasant, Rin is a nun, Len isn't mentioned (he's dead)...
So this would have had to have taken place before Miku is killed but; Len..? xD;;
But I bet GUMI's "Deadly Sin" chapter "Anger" will complete this story ouo;;