"Saikyuki" (record of court practices and usage, written by MINAMOTO no Takaaki in Chinese style) describes that the Emperor went to Butoku-den (an exercise hall) to watch a game of Dakyu on June 3, 727.
『西宮記』には5月6日、天皇が武徳殿に行幸し、打毬を観覧したことが見える。