Health and Sports Day - National holiday

tokyo ☀   25C
11 October, Monday - moon day, moon in Sagi. (the 4th day)

Sports day (the second Monday in Oct.)
It commemorates the opening of the 1964 Summer Olympics
held in Tokyo. - Wiki
Tokyo Metropolitan Gymnasium
(Built in 1954, and has been used in many games
including the 1964 Summer Olympics. Open to the public.)