Aku no Taizai: Nemurase Hime kara no Okurimono

Book three of the Aku no Taizai series.
"For the sake of your happiness."
Based on the song posted by mothy on Nico Nico Douga in May, 2011. The song with the theme of "Sloth" in the Seven Deadly Sins Series, it tells the story of Margarita Blankenheim: a girl who created a peaceful Gift for the troubled people.