Hina Matsuri (雛祭り) is a Japanese holiday in which dolls (雛人形 hina-ningyō) in traditional Heian period dress are displayed. It is a time in which Japanese families pray for the health and happiness of their daughters. Hina Matsuri is celebrated on March 3, although the doll displays usually begin going up at the end of February.
Hina Matsuri literally means doll festival or peach festival. It is also called Momo-no-Sekku (Peach Festival.) Usually, girls display their most precious dolls on a seven-tiered platform in their home. Families visit shrines and pray for the health and happiness of their girls. You can read the history of this celebration here.
I found a very interesting article that explained the link between the tradition of Hina Matsuri with one of the main seasonal festivals or gosekku: Jõshi.
“Japan’s Doll Festival has a very curious history, one largely forgotten in contemporary times. Held annually on the first day of the snake on the third day of the third month in the old lunar calendar (March three in modern times) since the mid-to-late Edo period (1600-1867), it was originally a day for ritual purification known in Japanese as Jōshi no Sekku 上巳の節句 (literally “Seasonal Festival of the Snake”) when people would rub their bodies with crude human-shaped figurines made of paper, straw, clay or wood. These figurines served as “scapegoats” for taking on (exorcising) the spiritual pollution and bad karma of the devotee. The word for snake (Jōshi) sounds like the word for girl (Joshi 女子), so the festival eventually became a day devoted to girls. Today the festival is a major joyous event but not a national holiday. Geared towards girls — the first sekku 節句 (seasonal festival) after the birth of a baby girl — it is a day when charming dolls are set out for display to symbolize the family’s wish that their daughter will be healthy, free from calamity and able to obtain a happy life with a good husband. Also called the Peach Festival or Momo no Sekku 桃の節句, as March is the season when peach flowers are in bloom.” (Source)
Nowadays, one of the main aspects of this festival is the celebration itself, there are all kinds of festivities which involve special limited editions, such as Hello Kitty-themed cakes. These cakes will go on sale for a limited time only at all ‘Moncher’, ‘Baby Moncher’ and ‘Forest Moncher’ patisseries nation wide, and will only be available for purchase from Sunday March 1st to Tuesday March 3rd. You can see them here. Other special sweets for this date include – among others -: hishimochi, sakuramochi, hina arare, manjū and shirozake.
There is also a very well known song Ureshii Hinamatsuri (Happy Hinamatsuri) for this especial day of Spring.
Akari o tsukemashou bonbori ni
Ohana o agemashou momo no hana
Go-nin bayashi no fue taiko
Kyo wa tanoshii Hinamatsuri
Let’s light the lanterns
Let’s set peach flowers
Five court musicians are playing flutes and drums
Today is a joyful Dolls’ Festivalｌ