Call it setsubun or call it risshun, February 3 is the day spring begins, at least on the calendar.
Just like the Roman calendar before Julius Caesar added his July or Augustus Caesar added his August, the old Japanese calendar is a little out of whack with the actual seasons as we know them. February 3 is too soon to get out your spring wardrobe, even in the southernmost part of Japan (Okinawa). It is a day for fun, nevertheless.
Fun consists of putting on your monster (oni) face for protection and flinging dried beans all around the house. Those beans can hurt, so be sure to wear the cardboard face mask that comes with the sack of beans. Buy extra, so everyone can have a mask. (cheapskates: rush the season even further and get out the swimming goggles)
You also have to say the magic words. The words are: Oni wa soto! Fuku wa uchi! (Devils get out! Good luck come in!)
Then comes the hard part, picking up the beans.
They are edible, a little like dry peanuts but not quite as sweet. You have to eat the same number of beans as your age if you want the charm to work.
Bon apetit!