Kingdom Hearts: Birth by Sleep is a Kingdom Hearts prequel developed and published by Square Enix and Disney for the Sony Playstation Portable (PSP), serving as the sixth installment in the Kingdom Hearts series. It was released in Japan on January 9, 2010, September 7, 2010 in North America, and September 10, 2010 in Europe. The game's name is shared with the secret video at the end of Kingdom Hearts II Final Mix, "Birth by sleep", which depicts a stylized version of a scene from the game. Kingdom Hearts: Birth by Sleep was developed by the same team that created Kingdom Hearts Re:Chain of Memories.