• South Korean actor Lee Joon-Gi as 4th Prince Wang So in SBS's 'Scarlet Heart: Ryeo.'

South Korean actor Lee Joon-Gi as 4th Prince Wang So in SBS's 'Scarlet Heart: Ryeo.' (Photo : YouTube/yeah TV)

South Korean actor Lee Joon-Gi showed his playful side in new "Scarlet Heart: Ryeo" behind-the-scenes-clip. In the ongoing historical drama, the 34-year-old star portrays the fearsome 4th Prince Wang So.

On Sept. 7, Wednesday, Lee's management agency, Namoo Actors Co. Ltd., released two backstage clips of SBS's "Scarlet Heart: Ryeo" through Naver V App. The first video showed the intense rehearsals Lee had with stunt actors.

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"Scarlet Heart: Ryeo" episode 3, which aired on Aug. 30 with nationwide ratings of 8.0 percent, saw the 4th Prince Wang So raiding the monk-assassins hideout. In order to keep the Dowager Empress Yoo's (Park Ji-Young) secret under wraps, the 4th Prince killed all the monk-assassins and burned their hideout.

The second video, on the other hand, featured Lee and co-star Lee Ji-Eun aka IU sitting on top of a mountain. The particular scene was reportedly taken on the first day of filming, which took place in the remote town of Yeongwol, Gangwon Province.

"I've been acting in a periodic series almost every year," The Kpop Herald quoted Lee as saying. "This makes it feel more comfortable while on set. IU did a great job as well, and I knew how to react while shooting."

Helmed by Kim Kyu-Tae, "Scarlet Heart: Ryeo" follows a 21st-century woman, Ko Ha-Jin (IU), who got transported back to the Goryeo Dynasty (918-1392). There, she awakens in the body of a 16-year-old Hae-Soo and got trapped in the conflicts and struggles between the royal princes of the ruling family.

"Through Hae Soo, viewers will be able to experience what it is like for a 21st-century person to enter the Goryeo period," a representative from the drama said in a statement obtained by Soompi. "They can enjoy watching her learn to adapt and grow."

The 20-episode historical drama is based on Tong Hua's debut novel "Startling by Each Step" (Bu bu Jing Xin). Other stars include Kang Ha-Neul, Hong Jong-Hyun, Nam Joo-Hyuk, EXO's Baekhyun, Ji Soo, Yoon Sun-Woo, Kang Han-Na, Jin Ki-Joo, Seohyun and Jo Min-Gi.

Check out "Scarlet Heart: Ryeo" behind-the-scenes clip below: