Shin-chan succeeded in making his mom buy a latest Action Mask toy sword for him. After they went home, something bizarre happened: his sword turned out as an ordinary bamboo stick. On his way back from kindergarten, Shin-chan saw a black dog which totally looks the same like Shiro. He named it Kuro and persuaded his parents to keep it at home. One day, a beautiful girl Puririn, came to Shin-chan telling him that she needs his help to return video to video shop. He opened the video shop door and that was the door to the dark world! While Shin-chan was about to go toilet in the midnight, a youth named Mata appeared before him. Mata is send to protect Shin-chan, he helped Shin-chan to defeat all kinds of enemies. Nonetheless, stronger enemies are approaching. How is Shin-chan going to save the world?