When you make an agreement in Japan, you are not just exchanging promises with another independent party. You are expressing and formalizing a relationship that involves mutual commitment, consideration, and ongoing obligation. The agreement exists within the relationship and serves it.
This means that when difficulties arise, the question is not just what the specific terms require but what the relationship requires. Terms can be adjusted if adjustment serves the relationship. The relationship is what matters; specific agreements are instrumental to maintaining it. Expect your Japanese partners to prioritize the health of the relationship over rigid enforcement of terms, and expect them to expect the same from you.