Prestel, a world filled with the atmosphere of the time when it went through industrial revolution remains.
There lives Klaus Valca, a 15 year old who using the Van Ship (a small flying ship) left behind by his father, made his home in the sky along with his childhood friend Lavie Head who is also 15.
Their dream was to surpass what their fathers couldn't do and that was to pass through the storm known as "Grand Stream". But, one day, a mysterious girl Alvis Hamilton, aged 11 is entrusted to them by the battle airship Silvana and they get dragged into a battle that shakes the world. The world of Prestel where a sea of wind and clouds stretch out.
The Grand Stream, sweeps across high in the skies.
Two countries that confront one another, Anatorel and Dysis.
Now, is the start of a terrible and exciting story!