People decorate the entrance of their homes with holly leaves with a dried sardine in order to protect their family against the devil. This custom comes from the tradition that the devil will be wounded by holly leaves and will be surprised by the smell of sardines, so he will be repelled from your house.
Setsubun is New Year’s Eve according to the lunar calendar. Scattering soy beans on the night of that day is an important event to exorcise evil spirits and welcome the New Year before the year god comes. To pray for good health in the New Year, there is also the custom of eating only the same number of soy beans as one’s age.
Taken from vol.7 PDF