The year he turned 31, while serving as a military doctor, he began serializing his first web novel, Gunuigwan, Igyegada, on Munpia and debuted under the pen name Han San-i-ga.
In 2018, he serialized the web novel Doctor Goes to Joseon. That year he also opened the YouTube channel Doctor Friends with the psychiatrist Oh Jin-seung and the internist Woo Chang-yoon.
In 2019, he became an ambassador for the Korea Hematopoietic Stem Cell Bank Association. He had pledged to donate in 2006 as a medical student and actually donated in 2016 while serving as a military doctor. In March that year he began serializing the web novel Trauma Center: Golden Hour on Naver Series, and in December it also began on Naver Webtoon.
On Jan. 1, 2020, he ended his hospital work and became a full-time writer. That August, Trauma Center: Golden Hour came out from Dasan Books as a five-volume set. In 2021, he was profiled in The Fact’s “Influencer Prism.” Doctor Friends then had 640,000 subscribers.
In 2022, he serialized the web novel The Black-Haired English Doctor. In January 2023, Ju Ji-hoon’s agency officially confirmed it was reviewing an offer to appear in Trauma Center: Golden Hour. In April, he appeared on a radio show and said web novel income was far higher than a doctor’s. In June, Netflix confirmed production of the drama and announced a cast including Ju Ji-hoon and Chu Young-woo. In November 2024, he began serializing Trauma Center: Surgeon Baek Kang-hyuk, a prequel to Golden Hour. In December, he also became a regular host of KBS2’s Secret of the Celeb Soldier.
The breakthrough yearOn Jan. 24, 2025, the year he turned 40, Netflix’s The Trauma Code: Heroes on Call was released in more than 190 countries. Within ten days it passed Squid Game 2 to rank first worldwide among non-English TV shows, and his name, as the source author, also began to become known.
In August 2026, he appeared on KBS2’s Malja Show and described plans to film season 2 of The Trauma Code. In September, he was appointed visiting professor at his alma mater, Inha University College of Medicine.
Lee Nak-jun (born Jun 2, 1985) debuted on Aug 22, 2016, the year he turned 31, with the web novel Gunuigwan, Igyegada, and became known on Jan 24, 2025, the year he turned 40, as the source author of Netflix’s The Trauma Code: Heroes on Call. On Aug 28, 2025 that year he received the Korea Creative Content Agency President’s Award.
Ages are by calendar year (the year minus the birth year), birthdays aside.