Tales of Vesperia: The First Strike takes place a few years after the end of the Great War before the events in Tales of Vesperia. The previous Emperor had just died and his position remains vacant with no heir appointed before his death, however the world seemingly remains in a state of peace. Utilizing the power of a powerful substance known as aer the people of the planet Terca Lumireis are in an age of discovery and prosperity. The crystallized form of aer which is known as Apatheia, is considered to be a very powerful energy source as it is essential to human life. In order to protect towns from attacks by monsters large amounts of Apatheia are being produced to create barriers around towns.