Why do Japanese people scatter beans on this day? And what does Setsubun mean?

Scattering beans to drive away the evil shall be performed on February 3, the Setsubun.
Putting up small decorations of sardine and eating beans, it is really strange.
Then why they do such things, let me explain it to you!

"Demons out! Luck in!"    Para Para (sound effect) "Mom! I killed the evil spirits!"    "Great, Thanks for your great help!" Then what is "Setsubun"? The name of "Setsubun" literally means "seasonal division", at this time, people will treat the evil spirits as ghost and drive them away.     “Ah〜” "The ghost hate smelly and sharp things, so the people put up small decorations of sardine heads and holly leaves (hiragi iwashi) on their house entrances so that bad spirits will not enter." "And... " "It was said that if one eats beans with the number equal to his life plus one, he will become stronger for the coming year."    "So delicious〜!" "Ah! Daddy!" "Where have you been right now? I've killed a evil spirit!"    "Sorry, I just went to the toilet ..."

What do you think?
On the Japanese Setsubun, you may be able to see something unusual.