Early Japanese lamellar armour , called keiko , took the form of a sleeveless jacket and a helmet .
Lamellar armor reached Japan around the 5th century , predating the rise of the samurai caste .
Early Japan lamellar armour , called keiko , took the form of a sleeveless jacket and a helmet .
Lamellar armor reached Japan around the 5th century , predating the rise of the samurai caste .