At Setsubun, you throw soy beans to cerebrate arrival of spring. The magic spell is "Oni wa soto, Fuku wa uchi (鬼は外、福は内)" which literally means "Devils out, Luck in."
This is called "Mamemaki (豆まき)"
For the family events, one of person wear "Oni men" which is the devil mask to be Oni. Lest of family throw Oni soy beans with "Oni wa soto."
When there is no Oni, you throw soy beans outside of your house from the gate with "Oni wa soto (devils out)", then throw them inside of the house with "Fuku wa uchi (Lucks in)."
After throwing Mamemaki, you eat specific number of soy beans, which is your age + one.
Also, you eat Ehomaki (恵方巻) " thick sushi roll" looking at the direction of the year. 2009 is eastern-north-east. Once you start eating it, you can't talk till finish.
You should do Mamemaki at night.