Shiena Kenmochi, No. 5 in Myojo Academy’s 10th Year Class Black, stands out among the twelve assassins targeting Haru Ichinose. Her frizzy brown hair twists into twin braided pigtails, framing brown eyes behind red rectangular glasses, while her uniform—a beige blazer, brown tie, and skirt—maintains a studious facade.

Severely bullied in her youth, Shiena found purpose in the online group Collective Dismissal after encountering Yukarin, trading revenge against her tormentors for avenging another member’s grievances. Before she could act, her assigned target was killed by Otoya Takechi, sparing her from bloodshed and making her the sole assassin in Class Black with no prior kills.

As Class Black’s hacker and strategist, she channels her meticulous nature into directing a *Romeo and Juliet* adaptation, blending organizational prowess with theatrical passion. Her assassination plan collapses during rehearsals when Hitsugi Kirigaya poisons her via a weaponized teddy bear, triggering health complications that force her expulsion—the fourth student eliminated.

Post-expulsion, Shiena infiltrates Myojo’s systems to expose Class Black’s secrets, driven by loyalty to Collective Dismissal’s collective goal rather than personal ambition. Though friendly and fiercely protective against bullying, her analytical drive is tempered by unresolved vengeance. Notably, she lacks a dedicated anime ending theme, and her official wish remains undisclosed. While her lethal potential remains untested, her expulsion redirects her focus toward hacking, leaving her long-term impact and interpersonal dynamics within the academy unrecorded.