The Demon Sword Master of Excalibur Academy, Vol. 6 (manga) by Yu Shimizu
After completing the mission at the abandoned city, its time for the eighteenth platoon to take part in the Holy Light Festival, jointly held alongside the Sixth Assault Garden. Their event of choice? A haunted cafe! Its not all fun and games, however, as Nefakesss dark influence begins to creep upon Riselia