The Armor types of the Tosei-gusoku were created after the Japanese had first contact with Spanish and Portogese Explorers who set foot on Japanese Soil while wearing their iron made cuirass in combination with chainmails. The Japanese adapted these armors and used the designs for their own creations. Another thing that changed japanese warfare was the import of matchlock arquebuses. The first and only firearm type the japanese adapted as well and used for about 200 years.