There are 24seasonal events throughout the year in Japan. Customs originally came from China, and those have been adapted to Japanese culture.
Setsubun- 節分- Today is the day of SETSUBUN. it depends on calendar, but usually around February 3 every year. This is one of the big events of the year because it has a meaning of dividing seasons, which stands for New Year's Eve.
In ancient Japanese custom, there was an event for get rid of evil and/or bad luck from previous year and wish for a luck in coming year by a yin-yang master at Court. A yin-tan master is similar to an augur or a fortune teller.
Scatter soybeans has started more than 1300 years ago as legend goes and is remaining as a signature and fun activity for this seasonal event.
The concept of throwing beans is traditionally get rid of evil. Then, you eat the same number of your age plus one (if you are age 25, you eat 26 beans) of roasted beans you just scattered and you will be in good health for the year.
Have fun in Tokyo!