Never wrote review for drama or movie but I have to write this time.
When this drama was released, I saw a few first episodes then stopped. It's because it's too dark and depressing. It's also long and very slow tempo compared to other Korean drama.
A few years passed and I kept hearing more and more people wrote and said this was the best Korean drama they ever saw, so I decided to try again.
If you pass the first tunnel which is dark and depressing, it will start touching your feelings and shaking up and down your emotions. I probably saw myself thru this drama and couldn't stop crying as I watched more and more.
After I finished this drama, I kept thinking what was life and what was happiness for weeks and months.
I am a guy who likes war, action, sf, and political movies and dramas but this is the best drama I ever saw.