Long ago, a war broke out in Japan that pitted Kantou against Kansai and divided the country. Kansai became dependent on Kantou, but slowly the police and government began losing control of Kansai to criminals known as Akudama.

Shin Chan gets his mother to finally buy him the last Ultra Hero sword, but when he opens the package there is only one rule inside. In addition to this confusion, Shin Chan meets Tostado, a dog just like Nevado but in black.