This small packet of paper is a United States Department of Justice Alien Registration Certificate. It contains critical information about the Japanese immigrant, in this case, Satoshi Yoshizato. It contains his name, address, picture, height, weight, color of hair, distinctive marks, and his fingerprint as well as other information. This comprehensive booklet was required to be carried at all times by any Japanese immigrant. The Japanese weren't allowed to be naturalized until after WWII, so this was an important document that allowed the U.S. government to identify these immigrants. There were strict rules on where the Japanese could go, and where their Certificate of Identification would be required to be shown. Even for people who had lived in the U.S. for many years, like Yoshizato who had lived in the states for 32 years.