Also known as: 足枷, 枷
Metal Cuffs used for restraint of the arms or legs, typically used in a Dungeon or Prison type setting when not used as an accessory.
They're similar to Handcuffs, but are more solid, wider, and frequently depicted as simply a solid band of metal around the leg or arm. They may be attached to something else, such as a wall or a Ball And Chain Restraint. Oni are typically seen wearing shackles.