Echidna is a wild elf from the southern tropical forests, specifically near Calibara Forest. A mercenary with over five centuries of battle experience, she possesses extraordinary combat skills, superhuman agility, and extensive warfare knowledge. She formerly led the Fang Assassination Unit and now operates independently. She has dull green hair with whitish bangs (turning fully white in her Unlimited form), red eyes, and stands approximately 162 cm tall (168 cm in Unlimited form). Her snake-themed armor includes a fur-collared vest, turtle shell shoulder plates, and shin guards. She notably uses her pet snake, Keltan, as a substitute for traditional underwear, often forgoing lower garments. In her Unlimited incarnation, her skin darkens significantly while retaining the snake motif in her equipment. Echidna's personality combines overt cruelty and sadism with a hidden compassionate side. She openly displays perverted tendencies, frequently groping or sexually harassing women she finds attractive, particularly Leina Vance and Claudette; this includes licking Leina's cheek, stripping her during sleep, and using sticky substances to bind her. Despite this predatory behavior, she secretly aids those in need and has cried in moments of crisis, embodying a "two-faced" nature with a cruel exterior masking a heart of gold. In combat, Echidna wields a curved snake-themed sword and a dagger, complemented by a shield bearing Medusa-like imagery. Her signature technique, "Black Rose," involves parrying attacks with her sword before countering with her dagger. She incorporates Keltan into battles, often having the snake bite opponents to inflict slow, painful deaths. Her combat parameters highlight exceptional defense, technique, and agility (all 5/5). She joined the Queen's Blade tournament under unknown employer instructions despite having no personal interest in the throne. Key relationships define her background: she is the former mentor of Irma, leader of the Assassins of the Fang. Echidna rescued Irma from execution after Irma's failed assassination attempt on Queen Aldra, but broken promises led to mutual resentment. Echidna also develops a recurring fixation on Leina Vance, citing her "curvaceous body" and "serious demeanor" as attractions while occasionally showing protectiveness, such as administering an antidote through a kiss. Her story continues beyond the main tournament. In later media like *Queen's Blade: Beautiful Fighters* and *Unlimited*, she retains her mercenary role, displaying a more playful combat demeanor. The Unlimited version alters her physical traits and fighting style but maintains her core characteristics. Her name references Greek mythology's Echidna, mother of Medusa, aligning with her snake motifs and agelessness.