Tokin (headwear)
The tokin (頭襟、兜巾、頭巾、ときん) is a small, black, box-shaped hat traditional to Japan, which yamabushi (mountain ascetic hermits) of shugendō wear on their foreheads. The tokin has been worn since the Kamakura period (1185–1333) or the Muromachi period (1336–1573).