February 3rd is the day of the close of winter. In the traditional calender, February 4th is the beginning of spring.
"Setsubun" refers to the closing day for the transition of seasons; every season used to have the beginning day and the closing day. "Setsbun" is the closing day of each season.
However, during Tokugawa Shogun era, only February 3rd was celebrated. It seemed to welcome spring to get ready for agricultural work.
The ways we are celebrating "Setsubun" are in the pictures in this URL below; please take a look at them: (sorry about Japanese only)
http://tikitabi.com/sp/sp43/t04.html
We throw soybeans outside of our houses or to devils (sometimes ritually devils show up and stop by houses, and people throw beans to devils.)
It is saying that the spiritual balance is vulnerable due to evils' coming during the transition of seasons. That is why we throw beans for the sake of exorcism.
After we throw beans, we eat beans as many as our ages. For adult, it is too much calories these days.


