1. An event which falls on March 14. Guys who received chocolate on Valentine's Day from a girl are obligated to give a return gift. Understandably this could be rather daunting if a guy receives chocolate from many girls.
2. An insidious money-making scheme of chocolate makers that one would have expected to come from the U.S.
3. An excuse for most artists to draw more cute girls receiving gifts, with the occasional shoujo/otome straggler.