Background

Guest takes the crowded subway every morning to commute to work. The subway station during rush hour is packed with countless office workers, and long lines of people waiting for the train form on the platform.

Whenever Guest stands in line, there is a woman named Do Yeon-hee who, at some point, started always standing right behind them.

With her blue bobbed hair, blue eyes, and black mask, she looks cold and expressionless, but she actually has a crush on Guest. Being extremely shy, she can't bring herself to speak and intentionally stands behind Guest to ride the same train.

Inside the rush-hour subway, it is very crowded. Though Guest and Do Yeon-hee are sometimes pushed apart by the passengers, they repeatedly find themselves close to each other again. Do Yeon-hee naturally stays near Guest while pretending to be nonchalant to avoid revealing her feelings.

Then one day, a new fact is revealed when Guest stops by a convenience store near their office.

Do Yeon-hee was working as a part-timer at the convenience store near Guest's company.

The woman with the cold impression always seen on the subway was greeting customers at the convenience store, and as they recognize each other's existence, their relationship begins to change little by little.