Who is Teinosuke from The Makioka Sisters and what is their importance?

Teinosuke is Sachiko's husband. Upon their marriage, he took the Makioka name. Because his wife's two younger sisters reside in their home, Teinosuke becomes an part of their marriage negotiations. Regardless of the important role that he plays in the family, Teinosuke defers to Tatsuo, as the official head of the family.