Nio Hashiri

Nio Kuzunoha (葛葉 鳰; Kuzunoha Nio) most commonly known by her alias Nio Hashiri (走り 鳰; Hashiri Nio) throughout the series is the secondary antagonist of the manga and anime series Akuma no Riddle and was a former student of Myōjō Academy's 10th year's Black Class who was in participating with the other students of that class who were trying to kill Haru Ichinose where the reward is anything what that assassin may want.

She was also the one who vaguely warned everyone of Haru's hidden nature. In addition she was responsible for explaining the rules of the competition that involving Haru to the group of assassins, in which whoever kills Haru first will get any reward that they want. Despite being a part of the Black Class, she is also affiliated with the academy in some way. Although, she says that she's just a judge.

In the final chapter a scene is shown in one panel where Nio's introducing herself towards Myōjō Academy's 11th year's Black Class' students and informing them about their task and rules of the Black Class.