The date of the festival was decided to be the day Emperor Kanmu was believed to enter Kyoto, on October 22, therefore, it is the birthday of Kyoto, the city that he decided to become the capital after moving from Nagaoka-kyo (the ancient capital of Nagaoka).
開催日も桓武天皇が長岡京から都を移し新しい都に入ったとされる日、すなわち京都の誕生日とも言える10月22日となった。