Awa Odori has been running in Tokushima every August since the late 1500s, which makes it one of the oldest surviving folk dance festivals in Japan. The story most locals tell is that the townspeople danced in the streets to celebrate the completion of Tokushima Castle, got carried away, and never really stopped. The form has changed over the centuries. The shamisen arrangements are more elaborate now, the troupes more organized. But the underlying rhythm, that driving four-beat yattosa pulse, has not moved.