The official website for the Akuma no Riddle manga has revealed that an anime adaptation will premiere in Spring 2014, as reported by Anime News Network. It also revealed the main cast.
The main cast looks something like this:
Ayaka Suwa as Tokaku Azuma
Hisako Kanemoto as Haru Ichinose
Yoshino Nanjo as Nio Hashiri
Azumi Asakura as Isuke Inukai
Additional cast members:
Fumiko Uchimura as Haruki Sagae
Mami Uchida as Hitsugi Kirigaya
Sachika Misawa as Chitaru Hamatame
Yuka Ōtsuba as Mahiru Banba/Shinya
Miho Arakawa as Sumireko Hanafusa
Haruka Yoshimura as Kōko Kaminaga
Chika Anzai as Suzu Shutō
Manami Numakura as Otoya Takechi
Yuki Yamada as Shiena Kenmochi
Tomokazu Sugita as Kaiba-sensei
Takahiro Sakurai as Mizurogi-sensei
Additional staff members:
Scripts: Masahiro Yokotani, Ayuna Fujisaki
Supervising Director for Weapons and Hand-to-Hand Fighting: Akira Otsuka
Action Director: Takayuki Sano
Colour Key: Ryota Nakada
Art Director: Masatoshi Muto
Director of Photography: Yasuyuki Itou
Editing: Toshihiko Kojima
Sound Director: Yoshikazau Iwanami
Sound Production: Dax Production
Keizou Kusakawa (Magical Girl Lyrical Nanoha A’s and Magical Girl Lyrical Nanoha films, il sole penetra le illusioni ~ Daybreak Illusion, Ro-Kyu-Bu!, Sekirei) is directing the anime at Diomedea.
Kiyoko Yoshimura is in charge of the series scripts, and Naomi Ide is the character designer and chief animation director.
Akuma no Riddle, or Riddle Story of Devil is a manga created by Yun Kouga and Sunao Minakata. The former is responsible for the story, and the latter is the artist.
The plot takes place at Myōjō Academy, a private girls’ boarding school. Haru Ichinose is the target of all the assassins in the 10th year’s Kurogumi class. Among those assassins is the newest transfer student, Tokaku Azuma. Although Haru is her target, she goes on to develop feelings for her.