Qual

Qual (クヴァール), also known as the the Elder Sage of Corruption (腐敗の賢老), was a demon who served the Demon King. He was a powerful demon who was feared during the Demon King's reign. Qual committed great atrocities in the region surrounding Größe Forest. He is the creator of the Killing Magic, or Zoltraak, the first piercing magic able to overcome all of mankind's magic defenses.

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, as upon hearing that Frieren had defeated him, he states 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. White, mask-like markings surround his eyes and dark markings recede into his hair line. He has dark skin covered by dark tattoo banding and staples that run across his face and body. Two ragged horns protrude from his head. Qual has long 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. He wears a fur shoulder cape, fur wrist cuffs, and a long, dark loincloth held in place by a chain and a string of tusks. His fingertips taper off in long, pointed nails. Qual is larger than most demons. In his sealed form, where he is crouched down, Frieren is only able to reach up to his knee.

History
Qual was the Elder Sage of Corruption. During the reign of the Demon King he caused great destruction in the Größe Forest, causing the death of the 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 Hero 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. As a result, Zoltraak and its counter defense became the basis of the modern human magic system. Frieren's seal on Qual remained intact for eighty years, though once a year Himmel was said to come check on the status of Qual's seal.

Twenty-seven years after the Hero Himmel's death, Qual is unsealed by Frieren. After being unsealed and realizing that the Demon King has 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
Zoltraak: His 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 being sealed, due to study by sorcerers across the continent, Zoltraak has become the basis for the modern magic system.

Trivia

 * Qual is German for 'agony'.