Japanese businesspersons typically dislike the use of overly explicit formal contracts. The preference is to have a basic contract that serves as a general guideline, and then iron out differences through a process of mutual compromise.
Compromise is most easily reached when each party is able to anticipate the wills and desires of the other. This ideal condition in which two individuals are “on the same wavelength” is known as ishin-denshin.
A state of ishin-denshin is of course more difficult to achieve when the two sides do not know each other well. Achieving a state of ishin-denshin is one objective of all the after-hours socializing in the Japanese business world. Nothing brings two parties together like a bottle of Suntory whisky and a mutual serenade in a karaoke / カラオケbar.
Ishin-denshin is also important in intra-company relationships. Japanese believe that colleagues who have close personal relationships will be apt to work together more effectively.