Girls' day

March 3rd is called " Hina Matsuri", the feast of girls' day.

This day, however , is not a national holiday, although Boys' Day, every 5th of May, is. 

To better understand why this is so, let us take a look at the history of ancient customs in the aristocrat era of Japan, so that we can understand why such unfairness happened.

More than a thousand years ago, only five days in the Lunar Calendar were regarded as feasts and were celebrated in accordance with ancient Japanese customs; January 7th, March 3rd, May 5th, July 7th and September 9th.  Those 5 days used to be holidays for ancient Japanese people; gender was never a issue.

It was only in the Edo period, during the Tokugawa Shogun regime, that the emergence of the Samurai class made somewhat radical change in the holiday celebration.
March 3 was originally referred to as Day for peach and eventually became known as Girls' Day.

On the other hand, May 5th became a day for a strong worrier, the Samurai.

Clearly we can see a distinction of gender at this point. Both dates were considered holidays and celebrated separately.

After the Tokugawa Shogun era, the Meiji regime changed the calendar from the traditional Lunar calendar to solar calendar and at the same time, holidays were reassigned.

Boys' Day and Girls' day were combined to one holiday as Children's Day on May 5th.

See the following URL.  (Sorry, this site is written in only Japanese)
http://www.mataro.co.jp/cpu/column/theme01/column06.php