
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.
LOTM: Witnesses of Sleepy Hollow Spin-Off - Firenza Junior[]
Nio is the secondary antagonist in LOTM: Witnesses of Sleepy Hollow Spin-Off - Firenza Junior as well as the most insane and immoral member of Langdon Orphans alongside Guinevere Arzonia. Nio in this storyline is much worse than her original counterpart from Akuma no Riddle, and she is the mastermind behind Carl's tragedy that killed his foster parents and all of his friends, while making Arzonia Brothers and Maria Arzonia her pawns. Nio is the catalyst to make Carl distrustful and bitter towards Maria even if he's in his own free will.
Technically, Nio serves as an arch-nemesis and a worse counterpart to Esther Blanchett, and she's the person who made Esther to turn against Langdon Orphans when Nio manipulated Esther's feelings to Abel Nightroad.