Hercule Barton, also known as Elly, operates as a core member of the Milky Holmes detective agency. Named after the fictional detective Hercule Poirot, she studies at Holmes Detective Academy in Yokohama during the Great Detective Era, where humans wield supernatural abilities called Toys.

Physically, she stands 151cm tall and weighs 46kg, maintaining a slim build. Her violet hair features spiky bangs and long side sections, paired with red Tareme-style eyes. She consistently wears a school uniform comprising a coat, dress, cape, boots, and ribbon accessories. Her birthday is October 21.

Personality-wise, Hercule exhibits profound shyness and social anxiety, struggling to speak in groups or tolerate observation. This timidity often obscures her attempts at logical reasoning. Yet she demonstrates quiet determination, expressing resolve through actions rather than words. To confront her fear of attention, she occasionally works as an art model, though this triggers recurring nightmares about being stared at. Among peers, she displays the most knowledge about mature subjects, reacting intensely to suggestive situations.

Her primary Toy ability grants superhuman strength, with documented feats including blocking sword strikes, shattering large rock formations, swinging construction excavators like baseball bats, and throwing beached whales effortlessly. When Milky Holmes lost their Toys, she uniquely reactivated her strength during critical emergencies.

In character development, Hercule formed admiration for thieves Mary and Kate after they rescued a cat, referring to them as "Onee-sama" (elder sister). She expressed wishes to reunite with them and reacted with visible awe to their presence. Within Milky Holmes, she shares close living quarters, including sleeping in the same bed as teammates. Observations of intimate interactions, such as Nero licking Cordelia, triggered intense blushing. Potential romantic inclinations surfaced in her reactions to Nero Yuzurizaki and Henriette Mystère's physicality.