Hyun-dong is a hikikomori. He lives off of the joy of assembling and displaying Gundams in his only space, his home. Then one day, he makes a big decision to go out to buy a Gundam plastic model that a delivery man left next to his door. At that moment, the front door slams shut. He is trapped in an unfamiliar world, he can't remember the password and he decides to go on a long journey to find the key house.
류준열
as Hyun Dong
Gwon Hyeokil
as Courier 1
Lee Kyungjin
as Courier 2
Kim Yunyoung
as Security Guard
Lee Minji
as Student
Mun Enok
as Young Hyun Dong
Lee Hyeonha
as Child 1
Lee Sangmin
as Child 2
Lee Kyungjin
as High school student 1
Han Hoseong
as High school student 2
Kim Hwanmyeong
as High school student 3
Ju Kihun
as Shop owner
