[Edaily Starin Gim Ga Yeong Reporter] As “100 Days of Lies” garners praise for its solid script, direction, and the actors’ outstanding performances, the actors’ foreign-language lines—which further enhance the production’s quality—are drawing attention.

On the 28th, the production team of tvN’s “100 Days of Lies” stated that, given the series’ historical setting during the Japanese colonial period and its focus on the role of interpreters, the actors devoted considerable effort to mastering a vast amount of Japanese and English dialogue. Director Yoo In-sik said, “From the moment they were cast, the actors enthusiastically prepared for their foreign-language performances. I was amazed that they were already speaking foreign languages at a high level during the first script reading.” He added, “Not only was the volume of foreign-language dialogue substantial, but there were also many instances where they had to interact directly with Japanese and English-speaking actors, so all the actors continued practicing day after day until the last day of filming (in some cases, for over a year). “Teachers specializing in Japanese, English, and Chinese provided one-on-one lessons with the actors, and whenever there was a scene with foreign-language dialogue, they would come to the set to review the actors’ lines one by one and offer guidance,” he explained.
According to the production team, Kim Yoo-jung devoted about five months before filming to studying Japanese. She didn’t stop at simply memorizing lines; she took three concurrent classes—covering grammar, conversation, and script familiarization—and attended two classes every day with almost no days off, despite her busy schedule. The main focus was on bringing out the character’s traits of quick thinking and resourcefulness, since Japanese and English were “survival languages” for Lee Ga-kyung. To master the speech patterns and intonation that suited Lee Ga-kyung, she first memorized her lines, then conceived the appropriate tone for the character based on the emotions and situation, and finally devoted herself to practicing again. Considering that Lee Ga-kyung’s character in the drama had picked up English by osmosis, she refined her performance by combining memorized words to create the impression of speaking off the cuff while practicing her English lines.
The Japanese language coaching team noted, “Actress Kim Yoo-jung was the first to begin her lessons. When she had overseas commitments, she even took remote video lessons between her schedule slots. She was truly excellent at internalizing every nuance of the accent and bringing it to life with her own unique touch; eventually, she became so attuned to it that she could detect even the slightest inaccuracy on her own—to the point where it was hard to imagine just how much she must have practiced,” they said, adding, “She was also highly skilled at freely adapting her delivery to her conversation partner, just like Lee Ga-kyung’s character.”
Park Jin-young, who plays the role of elite interpreter “Hideo Sato/Kim Tae-woong,” delivers both Japanese and English lines. “Practice was the only answer,” Park Jin-young revealed, explaining that he began in February of this year and repeatedly practiced only the Japanese portions of the script until all filming was complete. It was also intriguing to see how Lee Ga-kyung differentiated between American and British English in her performance, in line with the character settings of Hideo Sato.
The Japanese language coaching team commented, “Compared to other actors, Park Jin-young was able to handle basic Japanese. Since he knew how to write hiragana, it was impressive to see him memorizing his Japanese lines by writing them out in hiragana himself in a large sketchbook. He said he memorizes best when combining lines with movements, and it felt like he was rehearsing a play as he memorized his lines while thinking through his movements.” They added, “To find the right intonation and speech patterns for her character, we asked about three people to record their voices for her. She once mentioned that she listened so intently that the voices kept ringing in her ears even when she lay down to sleep. Despite the challenges of taking Japanese and English classes back-to-back, she always prepared with enthusiasm.”
Kim Hyun-joo, who plays the role of “Yoo So-ran,” took on the challenge of acting in Chinese. Although her character is a Chinese person speaking Korean, she is not a native speaker of the language; therefore, rather than striving for overly precise intonation, she focused on maintaining a natural flow, according to reports. Since there wasn’t much available material to confirm the linguistic characteristics of that era, she carefully observed the intonation and speech patterns of her Chinese teacher—with whom she took Chinese lessons—when speaking Korean. She also referenced the Korean pronunciation of various Chinese people to develop an intonation suited to her character.
The instructor who helped Kim Hyun-joo with her Chinese performance said, “Unlike Korean, Chinese has four tones, so we first focused on mastering the pitch variations and the points of articulation for each tone. “We then began by applying this to actual lines, starting with slowly mastering the pronunciation, and continued practicing until she could deliver her lines naturally,” the instructor added. “Actress Kim Hyun-joo concentrated intently on her practice, meticulously examining the pronunciation and intonation of every single line. What was particularly impressive was how she never missed even the slightest difference in pronunciation and constantly refined her delivery to make the lines sound natural. She maintained her concentration even while repeating the same lines countless times, and continued practicing after class by listening to audio files I had recorded for each line,” he said.
Director Yoo In-sik and the actors delicately portrayed the subtle differences between characters, even within the same language. One example was the Japanese lines spoken by Yoo Philip (played by Lee Mu-saeng). The Japanese language coaching team explained, “Actor Lee Mu-saeng came to his first lesson last winter having memorized almost all of his Japanese lines. For ‘Yoo Philip,’ we focused on capturing the feel of Japanese spoken by a foreigner. To better highlight the characteristics of Japanese spoken by English speakers, we showed him reference videos rather than relying solely on lessons,” they explained.
In fact, Lee Mu-saeng memorized his lines based on the idea that the Korean spoken by an American would differ slightly from standard Korean, gradually refining Yoo Philip’s unique way of speaking. Above all, he approached his performance so that the character’s profession as an international correspondent stationed overseas would be reflected in his linguistic expressions.
Jin Seon-kyu stayed in Japan for two months, memorizing the script for seven hours a day. He showcased natural pronunciation and intonation, even earning high praise from locals in Japan. The Japanese language coaching team said, “Actor Jin Seon-kyu’s first lesson was last October. When we heard he was going to Kyoto, Japan, for about two months, we were worried he might pick up a regional accent. So, we found an actor in Kyoto to help him with his Japanese lines,” they explained, adding, “During his two months in Japan, he studied Japanese conversation in the mornings, worked on his Japanese lines in the afternoons, and had twice-weekly remote video lessons with us in Korea to review his lines.” He added, “He even practiced lines in the Korean spoken by Japanese people, and the volume of material was so vast it was almost heartbreaking. Still, he pulled it off so well that I could only say how impressive he was.”
Finally, the Japanese language coaching team explained, “All the actors began filming only after memorizing 12 episodes’ worth of Japanese lines. So while there were occasional mistakes in Japanese intonation, there were almost no instances where actors couldn’t recall their lines on set. This is a result that couldn’t have been achieved without the actors’ hard work, even with the instructors present.”
“100 Days of Lies” is a tvN Saturday-Sunday drama depicting a 100-day espionage romance that unfolds when Gyeongseong’s top pickpocket, turned spy, and an elite interpreter for the Japanese Government-General of Korea meet in the heart of the enemy’s territory. Starring Kim Yoo-jung, Park Jin-young, Kim Hyun-joo, and Lee Mu-saeng, the series has been receiving critical acclaim. “100 Days of Lies” began with a viewership rating of 5.3% (Nielsen Korea/nationwide households) for its first episode and has risen to 9.5%. It is also gaining momentum through word of mouth, ranking 3rd in TV and OTT buzz for the second week of October, 2nd for the third week, and 1st for the fourth week.
It airs every Saturday and Sunday at 9:10 p.m.