Nero Yuzurizaki, a 15-year-old member of the detective unit Milky Holmes, stands 152 cm tall and weighs 42 kg, born on August 28. Her personality is distinctly tomboyish and selfish, marked by her use of the masculine pronoun "boku." She frequently talks down to others while indulging her substantial appetite for food and sweets. Despite these traits, she reveals underlying kindness and loyalty, often looking out for her fellow Milky Holmes members.

She possesses the supernatural ability known as a Toy, enabling her to control machines via a small metallic fragment. This power allows her to disassemble machines and reconstruct, enhance, or transform them into different configurations using surrounding materials. The full scope of her abilities remains largely undefined compared to her teammates.

Within the group, her relationships are complex. She exhibits a crush on teammate Hercule Barton and engages in physically affectionate behavior with Cordelia Glauca, including clinging to her while sleeping and licking her cheek after a game loss. She has also been observed staring at Cordelia's breasts following a cosplay incident, highlighting her blunt and unrestrained nature.

Her narrative centers on confronting the Gentlemen Thieves, particularly during an encounter where Milky Holmes loses their Toys. This defeat results in her and her teammates being forced out of Holmes Detective Academy and relocated to an attic. She participates in various efforts to regain their powers, including a museum incident where they destroy Milky Holmes-related artwork using their Toys before being subdued.