There are Japanese who are not Christians but who celebrate Christmas at home. They will buy Christmas cake and have a Christmas party. Nearly all Japanese families give their children Christmas presents on Christmas. In other words, the Japanese are able to easily adopt Western customs; similar to the way they are able to adopt English words into their language.
Valentine's Day began in the third century as a festival for the martyred St.Valentine. At first, the custom took on the form of parents and children exchanging cards with written messages that expressed gratitude. In the twentieth century, Valentine's Day became a day for both men and women to give presents to the other as a declaration of love, and also a day for the woman to declare her love to the man.
The Valentine's Day vogue of today had its beginnings in 1936 and 1952 when a Kobe confectionery, Morozoff, utilizing their shrewd commercialism in making the most of this custom. It began with a campaign for women to give chocolates to the man in their hearts. In 1958, another Tokyo confectionery took up this campaign and the custom became an instant hit among young women.
Around 1975, hoping that their luck would continue, White Day was conceived, which comes one month after Valentine's Day (March 14th). Men give the women whom they received chocolates from, chocolates back in return. Many see this as being quite unnecessary.