The story behind the story. (info from wikipedia)
Momotarō (桃太郎?, "Peach Boy") is a popular hero of Japanese folklore. According to the present form of the tale (dating to the Edo period), Momotarō came to Earth inside a giant peach, which was found floating down a river by an old, childless woman who was washing clothes there. The woman and her husband discovered the child when they tried to open the peach to eat it. The child explained that he had been sent by Heaven to be their son. The couple named him Momotarō, from momo (peach) and tarō (eldest son in the family).
https://youtu.be/mBMpZ2fFyZg?t=1m22s
The song behind the story.