Cha Hyun Su is a teenager who is addicted to video games. He only leaves the room when he has to, for example to eat or go to the bathroom. Once, Hyun Su’s mother asked Hyun Su to go on vacation with her family, but Hyun Su did not accept her mother’s invitation, so Hyun Su’s mother immediately left with Hyun Su’s father and brother, leaving her alone at home. On the way, an argument broke out between the father and mother, who thought that Hyun Su had been brought up badly and therefore had an unruly character. Because my father was caught up in the debate, he crashed into a truck, resulting in the death of the family.
Hyun Su, who lives with his family, is not saddened by the loss of his family, but expresses frustration that his family’s insurance savings are so small that it is difficult for Hyun Su to continue his life. He now moves into an old apartment called “Green Home.” A mysterious phenomenon has occurred in his life. The human figure turns into a monster, and this not only happens around him, but the whole world experiences it.
Cha Hyun-Soo meets Pyeon Sang-Wook, a man who lives in the same apartment. Pyeon Sang-Wook is a mysterious man with a somewhat harsh tone. Sometimes the other residents feel uncomfortable around him. The trapped residents have to fight monsters to survive.