Iwanu ga hana (言わぬが花): not saying it is the flower. Leaving something unsaid has more charm than saying it.
Kūki o yomu (空気を読む): to read the air. To sense the mood of a situation and act to suit it.
Hito o tateru (人を立てる): to put a person in between. In a negotiation, to let an agent or go-between step in between oneself and the other side. It also means stepping back so that another person keeps face.