also: しょじつ
Refers to the first day of an event, performance, exhibition, or similar occasion. Often used for sumo tournaments, theater runs, and movie releases.
The first day of the grand sumo tournament was a full house.
I went to the opening-day stage greeting for the movie.
The new stage production has finally reached its opening day.
This movie posted great results on its opening day.
I went to the theater on opening day to see the new release.