A school festival, where all the clubs compete in various activities. Not Japanese-exclusive, but far more common there than elsewhere. In the United States, they are referred to as Field Days, but for some reason they don't show up much in fiction.
Examples:Anime and Manga
- In To Aru Majutsu no Index, this gets a twist due to the espers. Powers are allowed in competitions, which means the lesser schools are inevitably completely shown up by the better ones, even with a handicap. Though Touma's class of Level Zeroes does surprisingly well, and not because of his Anti-Magic hand. It's because someone made their teacher cry.
- Haruhi Suzumiya has this of course, with the SOS Brigade winning every single event--most of those victories secured by Haruhi herself. Well, except for the relay race, where Yuki forgot to limit herself to human speeds. It's only much later that everyone remembers that the SOS Brigade technically isn't a club, so they shouldn't have been allowed to compete.
- In Ouran High School Host Club they decide to put on a sports festival. The typical 'bread eating race' is turned into a bread dining event, the bean bags are made by a famous designer, and the cavalry race is scrapped since they think that it would require actual horses.
- In Azumanga Daioh Chiyo-chan and pals participate. Chiyo is adorably slow, and can't get any bean bags into the basket in the bean bag tossing event. Sakaki stands out in the relay, and in the scavenger hunt, Karin has to find an 'idiot' She takes Tomoyo.
- In School Rumble, this is played in the same off-beat manner the show does everything. Ends with Eri spraining her ankle before she can compete in the relay, and then Harima promising to win the race for her. Then they dance together at the bonfire.
- In Revenge of the Nerds homecoming is celebrated with an Olympics-type series of events such as "riding a tricycle while consuming mass quantities of alchohol," the javilin, a burping contest, and a musical/sketch contest.
- When the school is turned into a dungeon in Fortune Summoners Arche asks if it's dungeon sports day.
Hello, Unknown Troper. You'll need to get known to lend a hand here.