Mio is a supporting character in the anime series Needless. She is a young girl with short pink hair and pink eyes, standing 147 centimeters tall. She is a member of Simeon's Pretty Girl Squad, a unit of female fighters who answer directly to Riru. Mio's fragment, the supernatural ability that defines her, is raw power, granting her immense physical strength. This strength is demonstrated by her habit of carrying an extremely heavy stuffed bear, which she insists is a rabbit.

Her personality is consistently cheerful, happy-go-lucky, and somewhat ditzy, even in combat situations or when she intends to kill. She rarely shows anger and is oddly unbothered by switching allegiances or associating with enemies. Initially, she infiltrates Adam Blade's group under the pretense of being an innocent girl attacked by a monster, exploiting Blade's well-known weakness for cute young girls. Despite her superficial airheadedness, she possesses surprising intelligence and notably advanced cooking skills.

Mio's primary motivation appears to be serving Simeon, though her loyalty is flexible and she can be swayed. Her role in the story is that of a spy and combatant who, over time, becomes drawn into the main group's conflicts. Her key relationships include her fellow squad members Setsuna and Kuchinashi, her commander Riru, and Adam Blade, whose protective instincts toward her create a complicated dynamic. While she does not undergo a dramatic personality change, her position shifts as the narrative progresses, and she proves capable of acting against her original faction. Her fragment of raw strength, combined with her deceptive demeanor, makes her a deceptively formidable opponent.