Girl's and Boy's Day
If you visit Japan during March or April, you'll notice that many stores or homes have a set of dolls or a miniature samurai helmet on display. This is to celebrate Girl's and Boy's Day.
Girl's Day was originally a ceremony to cleanse the home or town in the spring. Young girls sent paper dolls floating down the stream. Eventually, families started displaying dolls in the homes instead. In the Edo Period, families competed to see who could buy the most expensive dolls set. Nowadays, grandparents spend about 1,000-2,000 US$ on a new doll set when their granddaughter is born. This is displayed in the weeks before Girl's Day (March in most of Japan, April in Nagano and other rural areas). The superstition is that if you don't put away the set right after the holiday, the girl will get married late.
Boy's Day started more recently as a mirror of Girl's Day, and occurs one month after. The helmets are less expensive, and the holiday less publicized.

Cherry Blossoms by the City Hall