Earth, desolate and ruled by robots.

On the surface, robots were building a giant tower, while survivors lived quietly underground.

However, the remaining survivors were also being captured by robots one after another.

Nero, the protagonist heading for the rescue, meets a girl of the dragon race with "mechanical wings" on his way.

Who is she? What are the secrets hidden in the giant tower and the underground facility?

And will Nero be able to safely rescue the people———?