It is better described in the light novel, Lakan is actually unable to recognize faces (Prosopagnosia). He recognizes the parts a face is made of but not a face as a whole. That's why he replaces the faces with go stones for unimportant people and shogi stones for important people where he needs to asign a rank to the person. The only face he obviously recognices (up to this episode) is Maomao's. Shogi = japanese chess.