Hercule Barton, alias Elly, is a 16-year-old detective student at Holmes Detective Academy and a member of the Milky Holmes team. She stands 151 cm tall, weighs 46 kg, and has blood type AB. Elly possesses an intensely shy and passive personality, frequently leaving her unable to speak or participate in conversations, causing others to overlook her. Despite this, she sometimes attempts to act as the group's voice of reason, though her timidity usually renders these efforts unheard. When truly determined, she expresses her resolve through decisive actions rather than words.

She experiences profound discomfort when observed, struggling to endure even momentary attention. Among her peers, she displays the greatest awareness of sexual matters, evident when she fled in distress after being asked to pose with her legs spread wide. Hoping to conquer her shyness, she took a job as a posing model at an art center, an experience that resulted in recurring nightmares about being stared at by artists.

Her superhuman ability, known as a Toy, grants extraordinary physical strength. While Elly rarely used this power after the team lost their abilities, she successfully reactivated it during critical emergencies. Feats include blocking a sword strike from Stone River in the PSP game, shattering a levitated rocky mass controlled by Sheryl in the first season's finale, wielding a construction excavator like a baseball bat, and effortlessly lifting and throwing a beached whale. These moments highlight her as the only Milky Holmes member capable of accessing her Toy during crises despite the group's overall power loss.

In one notable episode, she became possessed by her ancestor, Hercule Poirot, altering her behavior and appearance. She may also harbor romantic feelings toward her teammate Nero Yuzurizaki.