The Shadow Agent was an unnamed woman who infiltrated Tenbi Academy during Minori Rokujou's enrollment.
Using her shadow possession ability, she was able to steal important documents from the principal's office by controlling a normal man who wouldn't appear on the room's Maken cameras, as they only detected ability users.
She was discovered to have used her shadow abilities to possess Nohana Saku before choosing to attack Minori and her classmates in her true body. After trapping the students in a shadow swamp, she was shocked to see Minori break free upon activating Dragon Ace. Minori then delivered a fiery punch of Element to incapacitate her.