White Day is celebrated in Japan on 14 in March, one month after Valentine's Day (Valentine's Day - Valentine's Day, where women and girls give chocolates and other gifts to men). On White Day, the men who received chocolate on Valentine's Day return the favor and give gifts to women.
White Day was first celebrated at 1978 in Japan by a Marshmallow candy factory when a candy maker Marshmallow began selling the idea to men that they should reciprocate the women who gave them chocolates and other gifts with white candy Marshmallows.
Soon, the chocolate companies realized that they could capitalize on that day as well and started selling the idea of giving white chocolate. Now, Japanese men give the candy white Marshmallows, white and dark chocolate, as well as other edible and non-edible gifts to women who were kind enough to think of them and to present them with chocolate on Valentine's Day a month earlier. The types of chocolates are the same too (Giri Choco, Honmei Choco, Tomo Choco, Family Choco, Gyaku Choco), bought depending on who the people will be gifted to.
Originally the day was called Marshmallows Day, only after a few years, that they decided to change to "White Day".