Like Christmas, Valentine's Day is highly commercialized in Japan. As you may know, on the day, women are expected to give men chocolate. Although I'm sure that confectionery and retailing industries took advantage of the day and popularized the costum, I don't know exactly when it became that common. Originally, in Japan, Valentine's Day was especially for a woman who liked a man but hadn't yet told him her feeling. Since it was believed that a man was supposed to first tell a woman that he liked her until probably three decades ago, Valentine's Day gave those women an opportunity of expressing themselves by giving chocolate. As the times have changed, women have become more aggressive in a positive way. On top of that, these days, a younger man often expects a woman to first tell him that she likes him, so I think that Valentine's Day has become less meaningful. Anyway, chocolate which a woman gives a man whom she really likes is called 本命チョコ/honmei-choko (本命 means the favorite and チョコmeans chocolate).
At office and school, women usually pass chocolate to their male friends and colleagues. If these men are those to whom they want to show their gratitude, they will be willing to buy chocolate for the men. On the other hand, if women feel under peer pressure to follow the custom and are reluctant to give chocolate to their colleagues, not only women but also men will find the custom bothering. Actually, women often have a hard time deciding to whom they are going to give chocolate while worrying about the total cost, and men are inevitably exposed to competition since many of them care about how many chocolate boxes they can get. On top of that, some women have ulterior motives. They view the chocolate as a lucrative investment. In Japan, if a man is given a box of chocolate by a woman, he will be expected to give a gift back to her on the 14th of March. It's assumed that the gift is supposed to be worth twice as much as the chocolate given. Because of this awkward custom, some women intentionally give chocolate to men who are likely to give luxury gifts back to them. Anyway, chocolate which women give to men out of courtesy are called 義理チョコ/giri-choco（義理 means obligation etc. ).
I assume that ”giri-choco” (chocolate for male colleagues and friends) largely contributes to its sales. However, as you can see, the chocolate often makes women feel like they are wasting money. So, I think that "giri-choco" has become less popular. At least, many women try to cut the budget for it. Under these circumstances, a new custom was created and has become very common in the past few years among school girls and young women. They exchange chocolate. This chocolate is called 友チョコ/tomo-choco (友means friends). Basically, women love chocolate more than men, so it probably helped the custom gain popularity.
I'm tired of customs created by industries and people making me feel like I need to follow the customs.
The website below: A confectionery company "明治製菓/Meiji Seika" built a bar of giant chocolate in front of itsfactory a week before Valentin's Day.
http://www.asahi.com/national/update/0208/OSK201102080057.html
