Qual

Qual (クヴァール), also known as the the Elder Sage of Corruption (の), was a Demon who served the Demon King and was feared during the king's reign. Qual committed great atrocities in the region surrounding the Größe Forest and was the creator of the Killing Magic, or Zoltraak, the first piercing magic able to overcome all of mankind's magic defenses at the time.

Personality
As a Demon, Qual is unable to experience human emotions including empathy. However, he is shown to be level-headed and calm, as upon being unsealed by Frieren, he is not angry and instead greets her like an old acquaintance. In addition, he demonstrates loyalty towards the Demon King: once hearing that Frieren had defeated him, he immediately decides that he will avenge the king. Qual has a strong faith in his magic, appearing surprised when Frieren and Fern are able to block a blast of Zoltraak. In addition, he is highly adaptable and analytical, shown when he immediately discerns the mechanisms and weaknesses of defensive magic and launches an appropriate counterattack.

Appearance
Qual, despite being a Demon, exhibits a monstrous appearance. His face features a square jaw, slanted eyes that appear stapled shut, and jagged teeth that are always visible. Light brown, mask-like markings surround his eyes and dark brown markings recede into his hair line. He has an ashy-brown skin tone covered with dark tattoo bandings and staples that run around his arms and across his body. Two ragged, yellow horns protrude from his head. Qual has long, light-blonde hair that begins in a tuft between the base of his horns and extends to the middle of his back, as well as a long beard which reaches past his waist. Qual's figure is larger than most Demons, and in his sealed form, where he is crouched down, Frieren is only able to reach up to his knee.

Qual wears a fur shoulder cape, fur wrist cuffs, and a long, dark-gray loincloth held in place by a chain and a string of tusks. His fingertips taper off in long, pointed nails and are colored red.

History
Qual was known as the Elder Sage of Corruption. During the reign of the Demon King, he caused great destruction in the Größe Forest, causing the death of about 40% of the adventurers and 70% of the sorcerers in the region. The source of his power was the magic he developed: Killing Magic, or Zoltraak, which pierced through all of mankind's defensive magic and equipment. During the Hero Party's adventure to slay the Demon King, he engaged in combat with them. Qual proved too strong for the party to defeat, causing Frieren to seal him as a last resort.

In the years after Qual was sealed, sorcerers across the continent analyzed his Killing Magic and developed countermeasures against it, with Frieren greatly contributing to the research. As a result, Zoltraak and its counterdefense became the basis of the modern human magic system, turning into ordinary offense and defense magic, respectively. Frieren's seal on Qual remained intact for eighty years, though once a year, Himmel would visit to check on the status of the seal.

Synopsis
Twenty-seven years after Himmel's death, Qual is unsealed by Frieren during her visit to a village in the Größe Forest. After being released and realizing that the Demon King had been defeated, he engages in combat with Frieren and her apprentice Fern. However, he is unable to break the basic defensive magic barrier conjured by Fern with his signature Killing Magic due to his spell being studied and incorporated into human magic systems. After trying to overwhelm the magic barrier casted by Fern with a multi-directional assault, he is defeated in one attack by Frieren using the same magic that he had created.

Abilities
Killing Magic: Zoltraak: Qual's signature magic spell, the first piercing magic developed in all of history which could pierce any of mankind's defensive magics or magic-resistance imbued equipment. After Qual was sealed, research by sorcerers across the continent led to Zoltraak becoming the basis for the modern magic system.

Trivia

 * Qual is German for 'agony.'