ノーリアクション

noun

no reaction; non-reaction; straight face

Describes a lack of visible response, often in situations where a reaction is expected. Can be used for a deliberately blank expression.

• 彼かれはその冗じょう談だんにノーリアクションだった。

  He showed no reaction to the joke.

• 大だい事じな発はっ表ぴょうのときも、彼かの女じょはノーリアクションを貫つらぬいた。

  Even during the important announcement, she kept a straight face.