Nio dou, one of the rarest styles of samurai armor crafted during the Edo Period, named after the Nio Guardian figures in Japanese temples. There were a number of meanings behind this style. One being it's close association with buddhism. The dou is embossed to resemble the emaciated torso of a starving monk or old man. These are also called "gakihara dou", after the starving ghosts of buddhist hell, another example is housed in the Tokyo National Museum.
Hon kozane maru dou (chest armor with true individual small scales, no hinge). Edo period samurai lamellar armor constructed with hundreds of individually laced nerigawa (rawhide) hon kozane (small scales). This is a maru dou (no hinge), this type of construction make a very flexible armor which conforms to the shape of the wearer.