Demon Sword Master of Excalibur Academy, Vol. 5 (light novel)

THE GODDESS'S CALLA recent rash of incidents has seen Holy Swords spiraling out of control and becoming twisted weapons known as Demon Swords. No one is sure as to the cause, but every Holy Swordsman affected claims to have heard the voice of a goddess, a detail that catches Leonis's attention. However, there's no time to investigate, as he and the rest of the eighteenth platoon are sent on a mission with other students to eradicate a Void Hive that crops up in Necrozoa-the site where Riselia found Leonis. So many Voids appearing in such a conspicuous place...could this be connected to the Demon Swords and Leonis's past?