1998–2003: Beginning in theater and Nanta
After graduating, Ryu joined the Dongrang Theater Company and performed in several large-scale musicals in a small roles. To support himself and gain life experience, Ryu took on various part-time jobs, including interior decorating, delivering food, carrying cabbage at Garak Market, and washing cars. Notably, he developed a unique venture on Jeju Island where he charged 30,000 won to take Polaroid photos of newlyweds flying paper kites with their wishes, a method that sometimes earned him approximately three million won per day. He also worked part-time at a bidet assembly factory in Jocheon alongside fellow actor Yoo Hae-jin.
A turning point in Ryu's career occurred in 1997 in New York, where he and Yoo Hae-jin performed the avant-garde play Duta (The Road to Gudo) at the La MaMa Experimental Theatre Club in New York. While there, he observed groundbreaking happening shows like Stomp, Blue Man Group, and Tube. These performances inspired him to question the prevailing didactic nature of Korean plays and the lack of similar non-verbal shows.
Ryu found his answer in October 1997, when he attended the premiere of the non-verbal performance Nanta at Hoam Art Hall, produced by PMC Production. Impressed by the show, he auditioned and became a substitute member, eventually joining as a core cast member in 1998. He worked closely with founding members Kim Moon-soo and Kim Won-hae, and later Jang Hyuk-jin, forming the ensemble that practiced and performed Nanta worldwide. The show quickly gained immense popularity, setting the record for the longest-running open run performance in Korea.
Following its participation in the 1999 Edinburgh Festival Fringe, Nanta embarked on a global tour across over 20 countries, including Japan, Europe, Australia, and North America, maintaining an audience occupancy rate of over 90%. It became a major cultural draw, attracting 70% of foreign tourists to Korea. Nanta was also the first Korean performance to utilize the concept of a dedicated theater, opening locations in Jeong-dong (2000) and Cheongdam-dong (2002). By 2003, PMC was operating seven theaters. The production made its New York debut in 2002, with a performance on Broadway and an appearance on NBC's Today Show, predating other major Korean acts like Psy. Ryu's dedication to Nanta lasted five years. He later reflected on this period, stating: "I had dreams of performing on Broadway. Nanta is a top-tier show... I eventually left because I felt like a mute without any lines."
After leaving in 2002, Ryu focused on roles requiring dialogue and reunited with director Jang Jin, having previously declined a script for Jang's play Heotang due to his Nanta commitments. They successfully collaborated on the play Welcome to Dongmakgol, performed at the LG Arts Center in December 2002. Although Ryu felt he had only regained about 70% of his original linguistic sensitivity after the performance, his acting skills were clearly evident.
