Tokyo Tower has been celebrating the coming of spring with a special Setsubun ceremony every year since the tower's opening in 1958. Start at the Main Observatory, where monks from the nearby Zojoji Temple will perform their rites. After which, you can join Noppon, the tower's official mascot, in the ritual throwing of beans and candies.
You should also try your luck at ehomaki munching – just remember you have to get it all down in one try. The 'lucky direction' for this year is apparently southeast, so point the monster sushi roll straight towards Tokyo Bay.