The story begins with the voice of the subway that runs the same tracks on the same time everyday while transporting people. The subway travels above and below 
ground and orbits its circular tracks. Rattle, rattle. The subway shakes a bit harder during the morning commutes to wake up those who fell asleep, and in the slower 
morning hours, it quietly welcomes passengers that it hasn’t seen in a long time. In the evening when many people throw their tired bodies into the subway, the 
subway stays still and looks at them. It listens to the invisible stories that fill the subway.
2020 3rd Lotte Publishing Culture Awards, Main prize
2017 Korea Publishers Society, Excellent Editing Book Award
2017 Children’s Book Association, Selected Book for Children and Youths
2016 Kyobo Book Store, Selected Book, No. 1 Recommended Book by Children's Book Editor