, or are forked roof finials found in Japanese and Shinto architecture. predate Buddhist influence and are an architectural element endemic to Japan. They are an important aesthetic aspect of Shinto shrines, where they are often paired with , another type of roof ornamentation. Today, and are used exclusively on Shinto buildings and distinguish them from other religious structures, such as Buddhist temples in Japan. Origin are thought to have been employed on Japanese buildings starting from the 1st century AD. Their existence during the Kofun period (250–538 AD) is well documented by numerous artifacts. Measurements for were mentioned in an early document, the , written in 804 AD. The evolutionary origins of the are not known. One theory is that they were simply interlocking bargeboard planks that were left uncut. Another is that they were part of a support system anchored on the ground to stabilize the roof. Yet another theory proposes that they were used to "pinch" and hold thatch roofing together. Evidence of this can be seen in , or common traditional homes, where two interlocking timbers are often found at the roof gables. However, the only certain fact is that were originally a working part of the structure, but as building techniques improved, their function was lost and they were left as decorations. were likely only to have decorated the homes and warehouses of powerful families, and more decorations signified higher rank. This tradition continued until relatively recent times. In the 17th to 19th centuries, the legal code dictated how many were allowed on building roofs in accordance with the owner's social rank. Today, are found only on Shinto shrines. Design may be built directly into the roof as part of the structure, or simply attached and crossed over the gable as an ornament. The former method is believed to closer resemble its original design, and is still used in older building methods such as , , and . that are not built into the building are crossed, and sometimes cut with a slight curve. While are predominantly placed only at the ends of the roof, this method allows them to sometimes be placed in the middle as well. More ornate , such as at Ise Shrine, are cut with one or two , or "wind-slots", and a third open cut at the tip, giving it a forked appearance. Gold metal coverings serve both protective and