Crayon Shin-chan: Fierceness That Invites Storm! The Hero of Kinpoko

Dark Lord of the Don Kurai dark world was plotting to try to dominate the human world. You have to know the dark legend of the "Hero" and the darkness Uchiharau as well as the "three treasures" one of which is the "tak of copper" that got stolen. A man who knew the plot of the dark lord is sent to the human world while trying to take the "shield of silver" and "golden spear" treasures of the remaining two.