Head plates were invented by an old forgotten clan that was obsessed with luck. Before battle they used prophets and shamans to predict where on their head the next fatal blow was due to land, then position the metal plate on their head accordingly. Sometimes it worked, sometimes it didn't. Such is luck, they would say.
Hachigane is armour equipped in the headgear slot. It belongs to the Light Armour Class and can be crafted using the Heavy Armour Smithy. The Side Angle Hachigane is exactly the same in stats as the Hachigane but has a different color bandana and positioning of the plate.