You'd be wrong.
As February 14th approaches, Japanese women prepare to give the men in their life dark chocolate. Yes, that's right, I said "men." Not just the man or the potential man. Japanese women give chocolate to their bosses and their coworkers, too. This is called giri choco or "obligation" chocolate, given to the men who have important—but non-romantic—roles in their life.
As for that special man she'd like to have in her life, he receives honmei choco. This chocolate is traditionally home made, but it's also acceptable to purchase expensive, high quality chocolates that have been made specially for Valentine's Day. If the woman is already in a relationship, the she'll probably give a little gift with the honmei choco to her significant other.
It's a huge deal. There was a little cake shop by the bus stop in a town where I had one of my schools. In January, display of big red heart-shaped boxes appeared in the forefront of the store advertising honmei choco you could preorder.
The idea behind this, as I was told by Waka-sensei, is that traditionally Japanese girls are supposed to be very shy. Valentine's Day is a chance for females to express their feelings to a boy without being singled out or putting themselves at risk of embarrassment. (All of this is very funny once you realized that Japanese guys expect women do all the work in the relationship. The woman says when and where they'll go out, how far they'll go, where they stand, etc.)
Sounds pretty one-sided, doesn't it? Well, the Japanese have the answer for that, too. On March 14th, White Day happens. White Day is when men give giri choco to their female coworkers who gave them chocolate the month before. This is traditionally white chocolate, but also white boxes of milk chocolate or sweets are acceptable. If a man given honmei choco by a woman wants to let her know that he feels the same way, he gives her a gift on White Day—I've heard white panties are popular.