"In this world, there are all kinds of perils! I'll teach you how to save yourself from those dangers, you moron!" So says Dangerous Jiisan, always looking out for his grandson. But, lacking any common sense...

It is the Sengoku period. ZubaBan is a wild child who is unbeatable in physical strength, he can easily swing around his giant sword and cut down hordes of enemies! Then, suddenly, Jeanne d'Arc, a knight clad...