My Status as an Assassin Obviously Exceeds the Hero's (Manga) Vol. 3

High schooler Oda Akira is good at flying under the radar. When his entire class is summoned to a fantasy world by a royal family, they're asked to become heroes and bring down the demon king... but Akira is suspicious. Using his stealth abilities, he sneaks into the royal library to find out the truth about this 'heroic mission.' Will he tell his classmates what's really going on, or is it up to Akira - and his remarkable thief-like skills - to solve this problem on this own?