The Demon Sword Master of Excalibur Academy, Vol. 4 (light novel)

Leonis continues his efforts to rebuild the Dark Lords' Armies to keep his promise to Roselia, the Goddess of Rebellion. In the midst of this, he and the girls of the eighteenth platoon are busy preparing a cosplay café for the large-scale school festival welcoming the Sixth Assault Garden. But while the festivities heat up, a Dark Lord buried in ice for countless years is about to be exhumed!