ーThe day the city had moved, our future began to move.ー
The year is 2018. Kashiwa City, Chiba Prefecture, Kashiwanoha Smart City. A family had come to the model room tour of the tower apartment in "Park City Kashiwanoha Campus The Gate Tower". With excellent facilities the family begins a new life in this city based on the environment. However, suddenly the after leaving, the ground shakes violently and a giant robot appears from where their tower apartment once stood. Or rather, their tower apartment has become a giant robot. The family is stunned. What the heck is happening in this town? What secret is hidden in this town?

[Source: Official YouTube channel; emended]