“…They’re classmates. And I know every one of them by name. Why should I worry about getting chocolate from them? I wasn’t the only one, so I don’t see any real reason to get suspicious of getting something sweet.”
“I’d have thought that everyone behaving very much out of the ordinary would have struck you as odd, Kuroba-kun… after all, this was something that was clearly pre-planned that you weren’t involved in. Does this happen often to you? You seem the sort to need to be abreast of every new development and the center of attention for every event.
"Regardless, I’ll end your suffering now. February 14th, the day that the girls (and a handful of boys) brought chocolate is known as Valentine’s Day. In the Western world, this is the day when people of all ages celebrate their relationships with others… It’s typically reserved for romantic and/or intimate love, but many choose to likewise show appreciation for their friends and family members, as well. In many ways, it’s similar to how the Japanese celebrate Christmas – as a holiday for couples and the hopeful lovers.”
“But while anyone can give a Valentine gift (flowers, cards, chocolates, stuffed animals, etc) to anyone else in the west, the custom in Japan (and some other Asian countries) is for the girls to give tribute to the person that they like in hopes that their love will be accepted and returned on White Day – March 14th. This is usually in the form of a gift of some sort… white chocolate, cookies, and marshmallows are popular choices among students, jewelry, white lingerie, and so on for adults.
"So you see, for the romantic, Valentine’s Day is the question – will you please be mine? – and White Day is the answer – yes or no respectively, with appropriate gift or horribly crushing silence.
"That said, like Valentine’s Day elsewhere, it is not strictly for lovers, particularly in modern day. "Courtesy chocolate” can be given to anyone, and is common among friends, colleagues, associates, etcetera.“
"You’ve now been informed about Valentine’s Day, Kuroba-kun, and the subsequent implications therein. I hope that you take it to heart; it’s not something that should be treated so lightly. After all, it’s likely that many of the chocolates that you were given were hand-made by those lovely young ladies, and if they never received anything from you on White Day, well… I’m certain you can guess what that means.”