Two OVAs released with the 8th and 10th volumes of the original novel. They fall chronologically between the first and second seasons.
Cast
Aikawa, Ayumu
Haruna
Hellscythe, Eucliwood
Seraphim
Ariel
Hiramatsu, Taeko
Mihara, Kanami
Orito
Sarasvati
Shimomura
Yoshida, Yuki
24 April 2012