What is the origin of Time Memorial Day?

It is a memorial day in Japan based on the historical event that in 671 Emperor Tenji used a water clock called a rokoku brought from China to give a performance using bells and drums and inform the public of the time. The day was June 10 when converted over to the solar calendar.

In response to the announcement made by the Alliance for the Improvement of Life in 1920 to be punctual and make daily life reasonable, June 10 was specified as Time Memorial Day.