If Sun-rok existed in real life, he'd be exactly this guy. Among K-Drama fans, Kim Jae-won's swoon-worthy moments in Yumi's Cells 3 are going viral. After TVING dropped Episodes 3–4, keywords like 'Yumi's Cells 3', 'Kim Jae-won', and 'Sun-rok swoon' started spreading across social media via retweets.
Fans are melting over the same point: he turned an early mistake into a total 'tsundere' move.
Even his mistake felt tsundere
Back in Episodes 1–2, PD Shin Sun-rok (played by Kim Jae-won) gifted writer Kim Yumi (played by Kim Go-eun) a premium dessert set at her studio—only to realize it was meant for a different writer. It seemed like a simple delivery mix-up, but the next day Sun-rok showed up again, shyly saying, "This is that dessert from yesterday," serving peak tsundere energy.
Maybe it was just polite follow-up—but drama fans are speculating, "What if Yumi's heart started to flutter from that very moment?"
That smile, game over
The exact moment Yumi truly fell for Sun-rok hits in Episodes 3–4: his smile. After Yumi presses him, a drained Sun-rok accidentally lets out a soft grin—goofy yet pure—and viewers were completely disarmed. On a business trip, he shows up in a more casual outfit and hairstyle, a fresh contrast to his work persona that catches Yumi off guard. When Sun-rok apologizes for the earlier misunderstanding, Yumi's heart starts to race. Once her dormant Love Cell wakes up, her feelings for Sun-rok bolt forward like a racehorse.
"Want to watch a movie together?"
Then comes the kicker at the end of Episode 4: Sun-rok asks, "Want to watch a movie together?" It's more than enough to set Yumi's heart on fire. "I thought you preferred watching alone?" she asks, flustered, and his sweet follow-up—"Want to watch together?"—cranks up the excitement and teases a big shift in their relationship.