Youmuin-san wa Yuusha ja Arimasen node

A certain girl genius with more power than knowledge accidentally summoned dozens of students and teachers into a dangerous world filled with beasts and magic, but the protagonist isn't a student or the homeroom teacher... it's the janitor. At the time of their summoning, the students and teachers each gained a power formed from their soul, but not the janitor. As the janitor was about to be bestowed with a power that would protect him, his power was forcibly taken from him by an arrogant stude...