Sora-age 14
Sora was chosen by the Keyblade to open the door. Although he doesn't know what the "door" is, he will learn... He wants to travel to other worlds with his friends, and is preparing to. Until one night, a terrible storm hit his island, and his friends disappear. He winds up in a mysterious new world, and sets off to find his friends.
Kairi-age 14
Kairi lives with Sora on Destiny Islands until she is swept away in the storm and Sora sets off to find her. She plays a bigger role in Kingdom Hearts than it seems, as you will find out...
Riku-age 15
Riku is like Sora and Kairi's older brother. He wants to explore other worlds with them. He disappears in the storm on Destiny Islands and reappears in various places. He seems to be up to more than exploring, though...
Goofy
Goofy leads the knights under King Mickey at Disney Castle. He is easygoing and hates fighting, but he will do whatever it takes to protect his friends.
Donald
Donald serves as King Mickey's royal mage. He is very impatient and gets into fights with everyone.
The Heartless
The many types of Heartless invade worlds and destroy them systematically. They have struck fear into everyone's hearts. Their purpose is to destroy the Keyblade master and let darkness reign supreme.
Ansem
Ansem used to be famous for researching the Heartless. It is said that he was killed doing so, but there is still nothing known about him currently.