SEE ALSO: Changmin searches for his first love in second 'Mimi' teaser

Changmin and Moon Ga Young were spotted concentrating on their script to act out the bittersweet first love story. Even when the cameras weren't rolling, they looked like a sweet couple with their V-signs, making fans curious about what they thought of each other.

Moon Ga Young fed fans' curiosity as she shared, "First off, I loved every minute of filming. [Changmin] is so handsome and treats me very well, so I was able to enjoy filming."

Changmin also shared, "Although it was very awkward at first to film a drama after three years, it was fun because it's been such a long time... I think Moon Ga Young, who plays my first love Mimi in the drama, is prettier than my real first love."

'Mimi' portrays the story of a popular webtoon writer Minwoo, who is on the search to find the first love he lost when he was younger. Changmin will portray both the younger version of Minwoo who falls in love at the tender age of 18 and the older version who lost her.

'Mimi' will premiere on the 21st at 11 PM KST!