Riddle Story of Devil

Riddle Story of Devil (悪魔のリドル, Akuma no Ridoru?, lit. "Devil's Riddle") is a Japanese manga series written by Yun Kōga and illustrated by Sunao Minakata. It was serialized in Kadokawa Shoten's Newtype magazine between the September 2012 and November 2016 issues. An anime adaptation directed by Keizō Kusakawa and animated by Diomedéa aired in Japan between April and June 2014. The series is licensed for streaming by Funimation in North America and Madman Entertainment in Australia. The original title is a pun on Devil's Trill (悪魔のトリル Akuma no Toriru?) by Giuseppe Tartini.

Plot
At a boarding girls' high school for trained assassins, one group;the black class,they target only one person -"Ichinose Haru". "Azuma Tokaku" is an assassin who transferred schools for a specific reason and is told to assassinate Haru,however she decided to protect her. Extreme school life, START!