TV-Series
Description
Nio Hashiri, originally named Kuzunoha Nio, joined the Kuzunoha clan as an unnamed orphan known only as "Chibi" or "runt." This clan mastered shamanistic illusion-based assassination. Adopted for her potential, she lacked formal education and exhibited rough behavior until entrusted to Myojo Academy's chairwoman, Yuri Meichi. Yuri disciplined her with a riding crop, taught her language and etiquette, and named her "Nio" after Lake Biwa's grebes—reflecting her Shiga Prefecture origins. Calling Yuri her "queen," Nio dedicated herself fiercely, undergoing the clan's tattoo ritual to cover her body in bird-like markings and amplify her service.

As Class Black's arbitrator, she enforced rules for twelve assassins targeting Haru Ichinose. Concealing her Kuzunoha heritage under the alias "Hashiri" (meaning "running"—chosen because she would "hurry anywhere for the chairwoman"), she avoided alerting Tokaku Azuma of the rival Azuma clan. Blending in via the standard uniform, she spied on classmates through a tablet, documented their wishes, and subtly hinted at Haru's past. Outwardly cheerful and energetic, she feigned ignorance of the assassination game's purpose while covertly manipulating events to sustain Haru as a target.

Her sociable facade masked profound antisocial traits: cruelty, deception, and near-total absence of empathy. She mocked classmates' suffering, smiled during Haruki Sagae's suicide attempt, and laughed at Sumireko's rooftop fall. Privately, she despised everyone in Class Black except Banba Mahiru and Shinya, calling affection "gross." Stemming from childhood neglect, tool-like training, and Yuri's conditioning, she lacked self-worth—accepting mistreatment and labeling herself "trash." Her sole authentic loyalty was to Yuri.

As the tenth assassin, Nio attacked Haru without warning. Using Kuzunoha illusions (hypnotic scents and mental manipulation), she impersonated Tokaku to make Haru die believing in betrayal, maximizing emotional pain. Tokaku thwarted the plan, exposing Nio during a knife fight. Though stabbed (chest in anime, back in manga), Nio survived. Collapsing, she mocked Tokaku as sharing a "rotten sea" origin. Later, she left a white rose at the unattended graduation ceremony.

Post-Class Black, Nio resumed arbitrating subsequent classes. When Haru succeeded Yuri as Queen Bee, Nio tearfully refused to acknowledge her, fearing Yuri's departure meant losing her "queen." After Yuri clarified Nio would remain her protector, Nio immediately smiled and vowed to follow her anywhere. They exited the academy via helicopter.

Nio wielded Kuzunoha illusory arts: distorting perceptions, crafting false appearances (e.g., Tokaku's guise), manifesting phantom weapons, and subjugating minds (as with Otoya Takechi). Her combat skill let her briefly rival Tokaku in knifework. Physically, she had short blonde hair, red-orange eyes, sharp teeth, and a 152 cm frame. She hid her tattoos beneath her uniform—black-and-yellow blazer, white shirt, red skirt, and thigh-high socks. Notable traits included melon bread preference, vegetable aversion, D-cup bust, and requiring only two hours of sleep nightly.