44th Period Survival Class

One day, mysterious holes called “Black Circles” began appearing all over the world. Their origin and contents were unknown—no one who entered ever came back.
When a Black Circle appeared at Do-yoon’s school, it grew larger and larger until it swallowed the entire building, dragging Do-yoon and most of his classmates inside.
Can they find a way out and escape the Black Circle, or will they be lost in the void forever?