In Japan Valentine is not celebrated as in Europe or North America. In Japan, on Valentine day girls are supposed to offer chocolates to boys. It can extend to nonlovers too: offering chocolate to your colleagues etc... Not to say that the chocolate business is at its climax and prices are skyrocketing. So a lot of people make their own chocolates and you can find all the necessary goodies in any supermarket.
Since I have a chocolate addict husband I can assure you the Japanese Valentine pleases him very much, and if we've never celebrated Valentine before we were in Japan, now I always try to prepare something. Usually it's chocolate truffles, and this year again that's what I'm preparing.
The recipe is simple and there is no possible way to make it wrong: melt 125g of dark chocolate with 40g of butter, then add 1 egg yolk, 40g of ice sugar, vanilla, stir well and keep refrigirated for 1h or 2h. Once the ganache is hard ise a spoon and roll some in yours hand then in cacao. You adjust the size to your taste.
Now I'm supposed to wait for White day (March 14th) for the counterpart present when boys are supposed to offer something to girls...