Ho-Su, who used to move a lot because of his parents work, finds a strange door in their new house. And he meets Seung-U, a boy of the same age who lives across the door.

The two boys, who shared a mysterious experience, began to come and go through the door. Warm air permeates between the two like a late afternoon. And slowly another secret grows in the hearts of the boys....

(Source: Lezhin, translated)