The youngest member of the male lead's squad,, he's like their youngest brother got really sick and it turns out he has a weak heart and he will die before he reaches his 20th birthday, all of them tried so hard to save his life and they did for now
Yun fainted while working on patients but off-screen (unfortunately for us ) so his colleagues gave him medicine intravenously but he needed extra medicine that's why his friend gave it to him then he started crying and saying My hands hurt but I want to operate again