Law of Glasses

Da-Min, a university professor, can only see distorted black space if he does not wear the glasses. However, there is a person who cannot be seen unless the glasses are not worn?! His name is He-Chan Min. Who exactly is he?

Original Webtoon:
Bomtoon, Lezhin, MrBlue, Naver Series, BookCube, Comico, KakaoPage