It's supposed to be a part of this improv thing they're doing with the new — "Otherworlders", they called it.

[she's trying to remain calm regardless of the situation; but it seems that Naegi is more frantic than she is... so she'll try to make him relax a bit.]

I just told you, didn't I? It's a princess and a prince costume. At least, that's what they said to me.