Chapter 5

Twenty-seven years after Himmel's death, Frieren drills Fern on defensive magic deep in the Größe Forest of the Central Lands. The shield burns mana fast, so the lesson centers on survival: rather than wrap herself in a draining full barrier, Fern learns to throw protection over a precise spot the instant a blow lands. Frieren keeps testing her by striking at openings, even from behind, until she is satisfied. The two then reach a village where an old man in a straw hat knows her on sight and walks her out to where the demon Qual lies bound.

Known as the Elder Sage of Corruption, Qual had ravaged the region eighty years earlier before the hero's band imprisoned him. Himmel, it turns out, returned each year to inspect the seal and foretold that Frieren would arrive once it neared failure. At the inn, Frieren explains that she bound Qual rather than killed him because he was simply too strong: a standout sorcerer of the Demon King's army who invented Zoltraak, history's first piercing spell, able to punch through every shield and enchanted defense humanity had.

The next day she breaks the seal and informs Qual that eighty years have passed and his master is dead. He looses Zoltraak in vengeance, but Fern deflects it with ease, baffled that such a famed spell behaves like any common attack. Frieren explains the irony: once Zoltraak was studied, mankind folded it into its own magic and built defenses that left it harmless. Qual deduces that shielding strains his foes' mana and sprays the spell in every direction, yet Fern, having drilled against exactly this, holds firm. Frieren then turns Zoltraak on its creator, and he crumbles into black dust. Back in the village, the grateful old man's hat jogs a memory of the boy who years earlier had flipped her skirt up, and the two travelers move on, Fern noting how deeply Himmel believed in her mentor.

Frieren and Fern destroy the demon once feared as the Elder Sage of Corruption, striking Qual down with his own Zoltraak. The chapter lays out how the once-unstoppable Killing Magic was analyzed and neutralized over the decades, becoming ordinary offensive magic. Himmel's yearly visits to maintain the seal and his faith in Frieren are revealed.

Killing Magic, or Hito o korosu mahō, debuted on May 27, 2020 in that year's twenty-sixth issue and runs twenty pages in the first volume. Part of the Beyond Journey's End arc, it introduces the demon Qual and adapts into the anime's third episode. The chapter notes that demons appear to experience time much as elves do, since Qual treats eighty years as trivial, and that across the surrounding region he killed roughly forty percent of adventurers and seventy percent of sorcerers with Zoltraak.