Actor Byeon Woo-seok / Courtesy of Varo Entertainment

The romantic drama "Lovely Runner" shattered its own viewership record of 5.8 percent in the finale, Tuesday, but the popularity of actor Byeon Woo-seok, who portrayed the K-pop idol Ryu Sun-jae, appears to be skyrocketing.

Taiwanese fans took over a billboard in New York's Times Square with photos of Byeon Woo-seok, while the song "Sudden Shower," which he performed in the drama as a member of the fictional K-pop band Eclipse, is dominating Melon's top 5. Additionally, his film debut, "Soulmate" (2023), is receiving a special re-release this weekend to capitalize on his rising stardom.

Reflecting on the drama that has garnered numerous fans obsessed with the so-called "Sun-jae syndrome," the 32-year-old actor said he can only attribute his success to "luck."

"I think there were many factors that contributed to the drama's success. The writer's penmanship was exceptional and the director's editing, directing and attention to detail were immaculate. It was a complex and well-crafted production. All these work out so well and I can't think of other words than sheer luck," he said during an interview with The Korea Times at a cafe in Seoul, Wednesday.

Byeon and his co-stars joined some 1,000 fans to watch the final episode of the drama together at a CGV theater in Yongsan District, Seoul, Tuesday. Recalling the live-watching event celebrating the series' final episode with fans, he admitted that he became very emotional.

"I tried not to cry, but I couldn't hold back during the final episode. There were so many beautiful scenes. Those scenes were in fact the result of the lighting director setting up hours in advance and the director of photography meticulously scouting locations," the model-turned-actor said.

"I was watching the drama in a theater with a lot of staff members and when the 16th episode ended and (staffers') photos came up, I felt a wave of gratitude and got very emotional. I think I cried because I loved and adored Sun-jae so much and it was a complex mix of emotions."

A billboard on New York's Times Square shows Korean actor Byeon Woo-seok. Captured from X @kdramasdiary

To play the role of a former swimmer-turned-singer, Byeon underwent two to three months of swimming training and received advice from co-stars for the concert scenes. Actor Lee Seung-hyub, who played Baek In-hyuk, Sun-jae's long-time friend and bandmate in the fictional boy band Eclipse, has been particularly helpful, since Lee is a member of the rock band N.Flying, according to Byeon.

"When I was recording the sound track, I tried my best following the details the music director pointed out, but due to the tight filming schedule, I couldn't spare a lot of time to practice the song. Seung-hyub and other Eclipse members, who are talented musicians, helped me and gave me advice on stage presence and performance," he explained.

Regarding his character, Byeon thinks Sun-jae's steadfastness and unwavering love resonated well with the viewers.

"I think fans have loved Sun-jae's enduring love, a love that echoes the resilience of a pine tree. One of my favorite films is 'The Notebook' (2004) and I have always wanted to take on the role of a man with deep love and devotion for a single woman, willing to sacrifice everything for his beloved. As Sun-jae is such character, I really loved portraying my character," he said.

The tvN rom-com drama, adapted from a web novel titled, "Tomorrow's Best," centers on Im Sol (Kim Hye-yoon), a huge fan of Sun-jae. Sol became paralyzed after an accident and finds comfort in Sun-jae's music. Then, disaster strikes again when top star Sun-jae dies in a tragic accident, leaving his fan Sol heartbroken. In a twist of fate, Sol travels back in time and wakes up back in high school, 15 years in the past — before her accident and Sun-jae's death. Seeing this as a miracle, Sol decides to use this chance to save her idol and rewrite their destinies.

Byeon Woo-seok plays K-pop idol Ryu Sun-jae of fictional boy band Eclipse in the tvN drama "Lovely Runner." Courtesy of CJ ENM

Asked what traits Byeon shares with his character, the actor said that he and Sun-jae both have emotional depth and intensity.

"I tend to fall for someone just like Sun-jae does, so in terms of intensity, I guess we're similar. But I don't think I'm as awkward as Seon-jae. He was quite clumsy when he was younger. Even in college, he was a bit awkward and unpolished when expressing his feelings. But from my perspective, I think I would have expressed myself differently. There are parts where he expresses himself as an athlete, speaking bluntly but sincerely, but I don't think I would have done that," he said.

In portraying Sun-jae at different ages in the time-slip drama, he said the most challenging part was acting during the scenes where Sun-jae recovers his memories from the past 15 years.

"When I played Sun-jae, not knowing the presence of Sol, I acted without emotions. However, the most difficult part was when I had to portray him regaining his 15 years of lost memories. I had a lot of trouble figuring out how to do it," he said.

However, his co-star Kim has been a tremendous support, particularly with her dedication and professionalism.

"Kim has this energy as Sol at shooting sites. The energy she emanates automatically turns me into Sun-jae and do the lines effortlessly. As this is the first drama that I've shot spending the whole day at the shooting sites, I failed to manage my condition at some points. But she went out of her way to bring chocolates and lift my spirits. "Seeing her, drenched in the cold during the scene but maintaining her professionalism, I realized how much I have to learn from her," he said thanking Kim.

With the popularity of the drama "Lovely Runner" still soaring, Byeon is taking his star power to meet fans across Asia. Starting in Taipei, Taiwan in June, he will embark on an "Asia Fan Meeting Tour" this summer with stops including Bangkok, Hong Kong and Seoul.