Chan lives every day like it is summer vacation. Haran is trapped in a lonely winter. When their forgotten past reunites them, Chan is determined to gift her another spring. Through laughter and tears, they face winter together and reach their spring in this heartwarming romance.
E1
Seven years after a lab blast changed his life, Chan returns to Korea and unexpectedly meets Ha-ran, a name he'd long buried.
E2
Ha-ran mistakes him for a stalker, but Chan is cleared. Reunited on a new project, he finds her changed and makes a surprising offer.
E3
Ha-ran rejects Chan's three-month friendship offer, but Chan is undeterred.
E4
As Chan and Ha-ran grow closer, a mysterious sound begins to haunt him, revealing gaps in his memory.
E5
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.
E6
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.
E7
Chan and Ha-ran reunite after his U.S. return. At a SHIM party, their bond grows while Chan starts recording his resurfacing memories.
E8
Ha-ran helps Chan reveal his father's watch secret. After their reconciliation, Ha-ran wins an award but meets a shocking face at the ceremony.
E9
Chan's unintentional lie about the fountain pen weighs on his conscience. To stay close to Ha-ran, he must decide if the truth is worth the risk.
E10
Chan's envy of Su-jin and Ha-ran grows. As Ha-ran celebrates Chan's birthday, she moves past her "winter" while Na-na makes a choice in Chuncheon.
E11
Ha-ran, who learns Chan's secret from seven years ago through the "1-Inch of Memory" notebook, falls into confusion upon realizing that even the fountain pen was a gift he had prepared.
E12
After their trial ends, Haran learns the truth. Chan has vanished, but discovering his feelings, she goes to find him.