Seven years after a lab explosion, Chan returns home for work and unexpectedly meets Haran again.

Chan sees that Haran is frozen in winter and suggests a three-month trial friendship.

Haran rejects Chan's three-month friendship offer, but Chan is undeterred.

As Chan and Haran grow closer, a mysterious sound begins to haunt him, revealing gaps in his memory.

Chan and Ha-ran find a Gyeongju escape but a resurfacing memory puts Chan in a brewing storm. Unbeknownst to Ha-ran, Chan is drawn into a brewing storm.

Chan's sudden exit for the U.S. leaves Ha-ran reeling. As longing sets in, the three sisters clash and Na-na faces an unexpected incident.

Chan and Ha-ran reunite after his U.S. return. At a SHIM party, their bond grows while Chan starts recording his resurfacing memories.