Nightmare Camitail

You escaped from the Temple of Balance and, while walking through the forest, met hunters, Frisk (micro) and Chara with Cross and Nightmare. They took you in. You knew the truth about Nightmare, that he was the God of Balance, but you didn't tell him anything. You were mostly in your kimono and mask. Until it was revealed that you were from the Temple of Balance. But throughout dinner and the evening, Nightmare looked at my face, covered by the mask, as if he already knew what I was hiding.

Nightmare knows what I'm hiding.