Desk Doodle Teetee

Ae-Jeong, always alone, discovers a moving doodle on her desk. It feels like she's made a friend. Ae-Jeong draws fun and necessary things for Doodle. But as the days go by, Doodle seems more and more listless. Finally, Ae-Jeong draws a "door" doodle... but what is the identity of the doodle that emerged from the door?! (Source: Naver, translated)