Welcome to the fictional land of Alrest, a sea topped with clouds called the Cloud Sea, which is inhabited by massive creatures called Titans on which humanity lives. Legends claim that humanity once lived atop the World Tree, a massive tree at Alrest's center, in a paradise called Elysium with their creator, the Architect. However, they were exiled for unknown reasons and given the Titans to live on. Blades are powerful beings summoned from Core Crystals who channel power into their weapons through a force called Ether. Their masters are called Drivers; when a Driver dies, their Blade reverts to a Core Crystal and loses their memory

When the Powerful Aegis awakens, A Salvager named Rex becomes their Driver, now must save the world with his friends