The colours of memories [Hyojin x Changyun]

Hyojin and Changyun have known each other since childhood. During their many years of friendship, they have made a thousand promises to each other. The most important: to remain best friends forever. The most ambitious: to go to the same university. The craziest: to move in together if they were still single at 40. But life decided otherwise and their paths diverged.
The years went by and they both grew older.
Hyojin is a documentary filmmaker whose work has allowed him to travel the world, and he got married. Following the news of his divorce, he decides to take some time off and return home.
Changyun is a brilliant journalist and writer, but has been unable to write since the death of his wife. He helps his parents, who own a restaurant, and raises his source of joy: his 6-year-old daughter.
What will their reunion be like after so many years? Will a long-buried secret come to light?