Time Day, also known as Time Memorial Day, is observed in Japan every June 10 to celebrate the history of timekeeping and emphasize the importance of punctuality. The date commemorates the installation of a water clock at the imperial court in Ōtsu in 671 CE, marking the beginning of official timekeeping in Japan. Established in 1920 by the Tokyo Astronomical Observatory and the Life Improvement alliance, this day encourages efficiency and the rational organization of daily life. While not an official holiday, it is widely celebrated by educational institutions and cultural organizations, which often hold lessons and exhibitions on timekeeping technology. A notable event is the Water Clock Festival at the Omi Shrine in Ōtsu, where representatives from the watch and clock industry present new timepieces and pray for the industry's success, alongside traditional performances and displays of ancient clocks.