Itterasshai means "Take care," "Have a good day," or "Please go and come back." This is the response given to someone who says "Itte kimasu." It's a warm send-off, wishing them a safe return. Parents often say this to their children as they leave. "気をつけてね、行ってらっしゃい！" (Be careful, have a good day!).

「行ってきます」と言った人に対して言う言葉です。無事に帰ってくることを願う気持ちです。「行ってらっしゃい！」