She Told Her Students She Was Too Sick to Teach. Then She Showed Up on Netflix.

WEDNESDAY, NOVEMBER 11, 2026

In South Korea, the CSAT is not just an exam. It is the morning the whole country rearranges itself around teenagers — and for the students in Lee Do’s online geography courses, it is the finish line of a year spent studying with one teacher. On October 29, three weeks before test day, those students opened a handwritten letter from Lee. Her health had failed, she wrote, on her doctors’ advice she would rest for the remainder of 2026, and the rest of her Korean Geography and World Geography courses — the final stretch of the curriculum — would not be taught. A week later, she was under the lights at a Netflix press conference, smiling into a microphone with her name on it.

Lee Do — also credited as Yido — is a Seoul National University graduate, trained in geography education, who teaches social studies for Etoos, one of Korea’s big online exam-prep platforms. She became famous the modern way: Netflix’s dating show Better Late Than Single turned a star instructor into a celebrity. The new show is The Devil’s Plan: Dead Again, Netflix’s brain-survival franchise, and on November 5 she attended its press presentation at the Mondrian Seoul Itaewon — six days after telling her students she was too unwell to finish their course. On November 7, she opened a personal YouTube channel and posted a video promoting the show. The lectures stayed stopped.

The students did the math out loud. Their criticism, reported by SBS and across Korean outlets, was not that a sick teacher rested. It was the order of events: the classroom went dark while the cameras stayed on. On November 9, Etoos apologized in her place — and its notice said the quiet part plainly. The company had coordinated schedules with Lee and supported the filming precisely so the lectures could continue; the agreed schedule, it said, was not kept, because of the instructor’s circumstances. All 17 of her courses were pulled or made private. The student Q&A board went private with them.

The show premiered on November 10. Lee was the first contestant eliminated, beaten in a one-on-one in the opening episode by the broadcaster Jaejae — after, Sports Chosun reported, pleading with the producers for her place in the game. That same day, she posted a second handwritten letter, and this one is different from the first in the only way that matters: it does not hide behind her health. “More than anything, I was irresponsible,” she wrote. “I knew far in advance that my health was not good, and I still told you I would stay with you to the end… What took that time away from you was not my health, but my own judgment.” She admitted she had failed to finish the curriculum for the second consecutive year. She admitted she had attended the press conference and launched the channel while her instructor’s work sat unfinished: “I fully imagine how disappointing that must have looked to you, who have to spend the remaining time alone.” She promised to suspend broadcast and personal activities until her health recovers, and to only ever promise lectures she can finish.

The apology has not closed it. Korean outlets have started filing the story under a colder label — Star News calls it “celebrity disease,” the sickness for which there is no medicine. And one student’s post, quoted by Sports Chosun, explains why the letters are landing flat: last year, when this happened the first time, Lee disappeared for months and returned with a single short notice, because the class was small and it never became news. “This year it became public, so the apologies keep coming,” the student wrote. “I guess the power of broadcast is real.” The post also notes when the apology arrived: the day the Netflix show premiered.

The CSAT is Thursday, November 19. Somewhere in Korea, students who bought a year of geography with a teacher who promised to walk them to the end will walk in without her — carrying her letter, her apology, and a gap in the curriculum where the final three weeks were supposed to be. Lee Do’s letter gets one thing exactly right, and it is the line her students deserved to hear in October instead of November: the time was not taken by her health. It was taken by her judgment.