The Demon Sword Master of Excalibur Academy, Vol. 6 (Manga): Volume 6 - Yu Shimizu

After completing the mission at the abandoned city, it's 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 café! It's not all fun and games, however, as Nefakess's dark influence begins to creep upon Riselia...