This document collection was collected and classified by Santaro Okamatsu himself, and left unnoticed from the researchers until 80 years after his death.
Included are letters, manuscripts and notes; copies of written expert opinions submitted to the court; drafts of legislations and notes on policies; and even catalogs of merchandise and receipts. These items speak for his achievements as a jurist, and his engagement to colonial governance of Taiwan and establishment of South Manchurian Railway Company.