IU has earned the nicknamed 'endorphin of the set'!

The weekend drama 'You're the Best, Lee Soon Shin' released still cuts of IU filming, and she was smiling brightly in almost all of them. Even though the drama's starting to take a sad turn, the set itself was never empty of laughter or smiles. IU was the perfect dose of endorphin the tired staff needed, going around to lift everyone's mood with a never-ending bright smile. 

The best picture is of IU meeting a caterpillar hanging from a tree while she was walking. She couldn't help but burst into laughter when she came face-to-face with it, which is charming as some girls would have shrieked in surprise.

IU said, "No matter how tired I am, I get full of energy when I'm on the set. The mood of the set is so great, and the other actors and staff are all so fun. I'm having such fun on set thanks to them."

The producers also said, "We think IU's hidden efforts in doing her best during shooting no matter how busy she was is the secret behind the popularity of the drama."

'You're the Best Lee Soon Shin' airs every Saturday and Sunday!