Once upon a time, a little old couple wanted a child, and so they prayed for one, no matter how small. Eventually they did have a son, but he was indeed small. They called him Issun-bōshi, which basically translates into Inch Boy.
As the boy grew older, but not bigger, he realized that how different he was, and decided that he needed to go out and find his own place in the world.
Issun-bōshi wanted to be like the great samurai in the stories his parents had told him, and so he traveled in a bowl as a ship, and used a needle from his mother as a sword.
He traveled down the river into the city, where he entreated the government for a position—and eventually he was assigned as a companion for the princess. The palace servants snubbed Issun-bōshi for his size, but one day as he was traveling with the princess, they were attacked by an Oni, or an ogre, who swallowed Issun-bōshi. Issun-bōshi then defeated the Oni by poking him from the inside with his needle sword.
After the Oni was dead and Issun-bōshi escaped, the princess picked up the mallet that the Oni had been carrying, and with its magical properties was able to turn Issun-bōshi into the size of a normal human. Eventually he and the princess wed and lived happily ever after.