The Mukkuri is a traditional musical instrument of the Ainu. The Ainu the indigenous people of Hokkaido, and are also thought to have been the original inhabitants of Japan. The Mukkuri is typically made from bamboo, is played by pulling a string connected to the instrument and is very difficult to play. The sound made by the Mukkuri is very similar to a jaw harp. However, about 1/3 of the way through the video, the sound changes to a very different and very distinctive sound.
AloJapan.com