What a coincidence that my birthday is on the White Day... White Day is an anniversary created in Japan in 1980. This culture not only spread in Japan but also was exported to South Korea and Taiwan. It is celebrated on March 14, one month after Valentine's Day. On Valentine's Day, women give gifts to men; on White Day, men who received chocolate on Valentine's Day return the favor and give gifts to women. This holiday is starting to gain popularity in Hong Kong, where Japanese influence is strong. The observance of Valentine's Day in Japan, particularly among students, is somewhat different than in the West. Valentine's day is mainly for the girls to present chocolates (either store-bought or handmade) to the boy of their choice. The concept of "Giri-Choco" (Japanese: 義理チョコ), which translates as "Obligatory Chocolate", has also developed, where a girl will give chocolate to those close to her (co-workers, for example) but in whom she has no romantic interest. When White Day rolls around, it is the boy's turn to return the gift in what is called "sanbai-gaeshi" (3倍返し) or "triple return", since the gift the boy gives is supposed to be three times the value of the gift received initially.
There are many theories about the origins of White Day. According to one, the holiday began in 1965 when a marshmallow maker started marketing to men that they should pay back the women who gave them chocolate and other gifts with marshmallows. Originally it was called Marshmallow Day, which was later changed to White Day.
Soon thereafter, confectionary companies began to realize that they could capitalize on such a tradition as well, and began marketing white chocolate. Now, Japanese men give both white and non-white chocolate, as well as other edible and non-edible gifts, such as jewelry or objects of sentimental value, to women from whom they received chocolate on Valentine's Day one month earlier.( source from Wikipedia)
