When Yoon had his vampire thingy going on his eyes went from very dark (black I think) to red, right? Now he drank Director's blood and they're lightblue? Does that make sense? Σ(  ̄□ ̄||)
I mean, I'm pretty sure he had blue eyes to begin with;;
Check the first episode, he clearly had black eyes Σ(っ°Д °;)っ
They slowly changed them to blue, though his eyes being darker may have been due to him being sick.
When Yoon had his vampire thingy going on his eyes went from very dark (black I think) to red, right? Now he drank Director's blood and they're lightblue? Does that make sense? Σ(  ̄□ ̄||)