Shokuryou Kyoushitsu

One night, Shou Uraya stumbles upon an eerie creature devouring another person. As he reels in horror, the creature makes eye contact and just as Shou thinks he's next for dinner, he blacks out. The next morning, he wakes up in his own bed, trying to decide whether it was all a dream... but when he arrives to class, he's greeted by a piece of paper stuck to the blackboard that claims one among them is a people-eating monster! As one classmate vanishes after the other, Shou and his classmates are a race against time to figure out the monster's true identity--or they're next!

(Source: Coolmic)