Kingdom Heart's is a video game series created by Disney and Square Enix in 2002. The heroes of the game are Sora ,Roxas,Riku etc...
The saga is a mixture of the universe of Final Fantasy and Disney.
In the game you can find universes or characters of Disney like Agrabah, Alice in Wonderland, Dingo, Donald etc...
Heartless are mad characters, the boss is Riku formely Sora's friend.
Today there are 11 different games because 4 games are "remix editions". The story of KH1:
-Sora lives on a desert island but one day he and his friend finds a door.
-Kaeri, the girl enters and she is teleported we don't know where.
-Sora run through the door and he finds himself in Travel Town.
-He explores different worlds to find his friend.