Masks have been an important part of rituals and plays in Japan since 10,000 BC. They were used to depict common people, deities, ghosts, heroes, animals, and devils. There are several varieties of masks including Gigaku masks which were the oldest and brought from Korea, Hannya masks which represent vengeful women, and Shikami masks which depict ferocious demons. The masks were made from materials like wood and lacquer and were used in important cultural practices and performances.