Kingdom Hearts Birth by Sleep

Kingdom Hearts Birth by Sleep is a pivotal action role-playing game in the Kingdom Hearts series, serving as a prequel that explores the origins of many key characters and events. It follows three Keyblade wielders—Terra, Ventus, and Aqua—on their separate journeys to find a missing Master and protect various Disney worlds from a new threat called the Unversed. The game introduced innovative gameplay mechanics and significantly expanded the series' lore.