South Korean drama "Descendants of the Sun" has broken the 30 percent viewership mark here after nine episodes, data showed Thursday.

The series, starring actor Song Joong-ki and actress Song Hye-kyo, was watched by 30.4 percent of TV viewers across South Korea on Wednesday, data by Nielsen Korea showed, marking the first time the nationwide figure has surpassed the milestone.

The show was the most popular among viewers in Seoul at 33.9 percent. In and around Seoul, the figure was slightly lower at 31 percent.

"Descendants of the Sun" tells a story of love between South Korean special forces Capt. Yoo Si-jin (Song Joong-ki) and Dr. Kang Mo-yeon, who volunteers at a medical nonprofit organization, in the fictional war-torn country of Uruk.

It premiered on Feb. 24 in South Korea on KBS 2TV and China on iQiyi, a Chinese video web platform.

In episode 9 that aired Wednesday, Kang tries to avoid Yoo after the voice recordings of her "will," in which she confessed her feelings for him, got broadcast across the barracks on accident. She had recorded it on her phone when her car almost fell off a cliff.

Not quite as swift as Yoo, however, she runs into the captain but is reassured.

"Don't think you lost because your feelings got exposed. I'm the one who likes you more anyway," he says.

Kang finally concedes and tells him straight how she feels.

When Yoo asks if she is among the volunteer doctors heading back to South Korea, she says, "No, I'm not going because of you. I'd like to spend more time with you. I think I just confessed how I feel. Should I apologize?"

In the next episode, Yoo and Kang get in trouble after trying to save children taken hostage by gang members in Uruk.

"Descendants of the Sun" airs Wednesday and Thursday nights at 10 p.m. in South Korea. In China, new episodes are released on the video platform iQiyi. (Yonhap)