Girl's Day is celebrated on March 3rd. It is also known as Doll's Festival or Peach Blossom Festival.

I think we should celebrate it also, hey, girls?

"This is a celebration day for girls, marked with a display of dolls in the best room of the house. All are displayed on a doll-stand or hina-dan which is a tier of shelves, usually five or seven feet wide, covered with bright red cloth. The dolls on display are often handed down through generations, antiques rather than toys. Parents who do not possess such heirlooms buy new sets of dolls for their daughters, and relatives and friends might make dolls.

The dolls which have pride of place are the DAIRI-SAMA, representing the Emperor and Empress, and are dressed in their ancient court costumes of silk. The Dairi-sama sit on the top shelf, the Empress on the right and the Emperor on the left as you face them. Behind them are miniature folding screens, which also form a background for decorated toy candle-stands and vases with peach blossoms. Court ladies and musicians, ministers, court officials and delicacies of many kinds in beautifuly decorated miniature boxes are placed on the lower shelves. Peach-blossoms signifying the feminine characterisitics of softness, mildness and peacefulness, as well as happiness in marriage, also adorn the stand.

The dolls may be put out some time before March 3rd, but they must be taken down before March 4th, otherwise (so the legend goes) the girls of the household will never marry!"

from
http://www.jfet.org.uk/JIF/Autumn95/year.html