MIHEE(35) appears at SUNGSOOK(42)'s door, and claims to be her childhood best friend. It's the first time they meet each other. Despite the fact, Sungsook lets Mihee in. Why did I do so? During the process of asking oneself and each other, they become friends.

A young woman in her 20s, Chae Meehee, visits middle-aged Cho Sungsook and insists that they were once childhood best friends. Though Cho Sungsook has never seen Chae Meehee before, they become closer at Meehee's insistence. Their pasts cross paths as though they were traveling through time.