Ku Hye-sun posted a photo on his own instagram along with a sentence "Tunzun started Exercise" on the 20th.
The picture shows the appearance of Ku Hye-sun who is seriously listening to The Lesson, diving by Skin Scuba in the indoor pool.
Also, Ku Hye-sun first released The Lesson video. In the image Ku Hye - sun is swimming freely under the guidance of the lecturer.
Meanwhile, Ku Hye-sun appeared in a swollen appearance than usual at the opening ceremony of "Bucheon International Fantastic Film Festival" held on December 12, and it was wrapped in a pregnancy theory, shaping theory and so on. Ku Hye-sun explained this directly as "Weighed a lot of rice, 10 kg."