aku no musume (series)
Major arc of Evillious Nendaiki, named after the eponymous song which spawned the series as a whole. Tells the story of Riliane Lucifen d'Autriche's disastrous reign as princess and the aftermath. Also known as "Aku no Monogatari".
The story was adapted into 4 novels, Aku no Musume: Ki no Cloture, Aku no Musume: Midori no Wiegenlied, Aku no Musume: Aka no Praeludium, and Aku no Musume: Ao no Praefacio.