Idk but there is a vamp I think what looks like the director but the director has light blue eyes and the vamp version has a grey and dark blue I think
Change in art style. Thats all, the first fee chapts have a different style if you notice, and they decided to make his eyecolour more prominent. Also the director and look alike vampire actually look quiet different if you put them next to each other
I thought it was because doyoon was just getting gradually weaker and he was struggling to keep up his human appearance, which made his eyes lighter and lighter to the point of getting red.
I'm wondering about one thing, in the beginning doyoon's eyes were black and after few chapters they became gray, light blue. Is there a reason or was it just an author's vision?