White Day (ホワイトデー, Howaito Dē) is a day that is marked in Japan, South Korea, Vietnam, Taiwan, and China on March 14th, one month after Valentine's Day.
In Japan, Valentine's Day is typically observed by girls and women presenting chocolate gifts (either store-bought or handmade), usually to boys or men, as an expression of love, courtesy, or social obligation.
On White Day, the reverse happens: men who received a honmei-choco (本命チョコ, 'chocolate of love') or giri-choco (義理チョコ, 'courtesy chocolate') on Valentine's Day are expected to return the favor by giving gifts. Traditionally, popular White Day gifts are cookies, jewelry, white chocolate, white lingerie, and marshmallows. Sometimes the term sanbai gaeshi (三倍返し, 'triple the return') is used to describe the generally recited rule for men that the return gift should be two to three times the worth of the Valentine's gift.
Today many Japanese do not understand or believe me when I mention the lingerie thing, because it is no longer popular. But it’s true, when I first came to Japan gifts to women of white panties were still a thing. People think I’m joking or lying when I say it. I’m not, though. I think on the one hand the gifts have evolved over the years, and on the other hand the people I am talking to are just too young to know any better. When I first came to Japan there were a number of things that were more common than they are today that are not within the social memories of younger Japanese and that have faded from the memories of older ones: vending machines that sold women’s underwear, both clean and soiled; vending machines that sold girls’ used high school uniforms (a common sexual fetish here); vending machines that openly sold pornographic comic books; vending machines that sold batteries; vending machines that sold alcohol (disappeared from the streets since the law was amended to allow convenience stores to sell beer and spirits). And there are a few things that did not exist - technological things like E-mail, Google, Amazon, Skype, Facebook, digital cameras, laptop computers, iPhones and DVDs, but also everyday things like garbage separation and recycling, and external advertising on buses and trains, which is now ubiquitous.
White Day was first celebrated in 1978 in Japan. It was started by the National Confectionery Industry Association as an "answer day" to Valentine's Day on the grounds that men should pay back the women who gave them chocolate and other gifts on Valentine's Day. In 1977, a Fukuoka-based confectionery company, Ishimuramanseido, marketed marshmallows to men on March 14, calling it Marshmallow Day (マシュマロデー, Mashumaro Dē).
Soon thereafter, confectionery companies began marketing white chocolate. Now, men give both white and dark chocolate, as well as other edible and non-edible gifts, such as jewelry or objects of sentimental value, or white clothing like lingerie, to women from whom they received chocolate on Valentine's Day one month earlier. Flowers and other gifts are also given on this day.
In Japan, if chocolate given to a man a month prior was giri choco, the man may not be expressing actual romantic interest, but rather a social obligation.
Eventually, this practice spread to the neighboring East Asian countries of South Korea, China, and Taiwan. In those cultures, White Day is for the most part observed in a similar manner.