I recently watch the ongoing series named one ordinary day (played by 김수현)
I surprised that the main role is asthmatic

So i wondered, is there any korean drama with asthmatic male lead?

I haven't found any Kdramas with ML with asthma, but there are a bunch of Cdramas with ML or second ML, also thai. I know of a Korean movie with a second lead with asthma tho.