Noh actors never should use their face. This also applies to those singing in the chorus. Arching your eyebrows during a lyrical passage, opening your eyes wide during a fierce passage, all this might be ‘natural’ (actually I don’t think it is) but it lets your emotions appear on your face. This is all too normal, too ‘everyday life’. It shows that you are not in control/aware of your face. It also distracts the audience. What is the reason why a Noh actor or chorus member should show their emotion to the audience? In Noh, there is no such reason. Keep your face still. Let the audience feel what they want to feel.