In fly fishing, Japanese Flies are artificial flies commonly found within many fishermen's tackle box in Japan. In addition to the usual lure variations of fishing grounds chosen by the fishermen and standard materials used in many regions, several differences are seen in the overall construction when compared to Western-style flies. Feathers, yarns and furs are all used, some of the most popular being peacock feathers, chicken down and neck feathers, and black wool. Some flies are even tied with thin copper wire to add extra weight so they can sink in fast-moving mountain waters. These special flies are mainly used in the Nikkō National Park area near Ashio, Tochigi Prefecture (前日光足尾).