While certainly not a national holiday, November 1 is "Sushi Day" ("Sushi no hi" or すしの日) in Japan. Good news if you love sushi.
Sushi Day was started in 1961 by the country's sushi guild as a way to promote the food. November was selected because it's after the rice harvest and seafood is especially delicious during this period. Also, 11/1 looks kind of like sushi-that is, if you turn your head sideways!
To mark the day, conveyor belt sushi chain Sushiro is giving customers one piece of complementary supreme tuna belly (honmaguro otoro or 本鮪大とろ) sushi per customer. You can see how it compares to the different grades of tuna below (left to right, supreme tuna belly, medium fatty tuna, and tuna):
Japanese website Gigazine popped by a Sushiro to get a free piece of sushi-and from the looks of it, gobbled up some more.
As far as inexpensive conveyor belt sushi chains go, Sushiro is perhaps my favorite.