Valentine's chocolates are given not only for an important person but also for people whom a person have social relations with(for example, coworkers and classmates).
A chocolate for someone a person likes is called "Honmei-choco[本命（ほんめい）チョコ]". On the other hand, a chocolate for someone whom a person is socially connected to is called "Giri-choco[義理（ぎり）チョコ]".
And men give women gifts such as cookies, candies or white chocolates in return for the Valentine's gift on March 14th, this is called "White Day[ホワイトデー]" in Japan.
The gift of Giri-choco is not compulsory but many women present that because that is thought as an implicit social etiquette. A man who gets Giri-choco from a woman must give the gift the woman on White Day.
But many people do not that positively and some think that as a bad habit because they must spend money and time for that although it doesn't have much meaning. Therefore, some companies prohibit that.