From the asakusa-umai.ne.jp website:
Kinryu-no-mai (Golden Dragon Dance at the unveiling of Asakusa Kannon) [March 18]
The official temple name for Sensoji Temple is Kinryuzan (Mountain of Golden Dragon) and this name comes from a tale about a golden dragon. According to the legend, 1000 pine trees suddenly appeared overnight near the temple on the 18th day of March. After three days, a golden dragon measuring 100 shaku (approx. 30 meters) descended into the pine trees from the heavens and was never seen again. The Golden Dragon Dance is based on this story. It was first presented in October 1958 to celebrate the opening of Showa Hall of the temple by the Asakusa Kannon Association as a commemorative event to be passed on to future generations. The dance is held on March 18 when the temple's sacred image is unveiled for public viewing and on October 18, an auspicious day for the Kiku-kuyo (Memorial Service for Chrysanthemums).
Under the direction of the late Mantaro Kubota, the Kinryu-no-Mai dance was produced by Yoshio Yoshikawa, scored by Yoshiaki Machida and choreographed by Fujima Tomoaki. It is performed by more than 70 male volunteers from local youth organizations who first purify themselves before devoting themselves wholeheartedly to the dance. The Kinryu-no-Mai has become an established well-known local event.