Over the Summer break, Gash and his crew opt for a picnic at Fuji Mountain but end up encountering a mystical book-wielding girl named Kotoha. She reveals that Gash's mother is located in a forest cave, as per her book's message. Upon reaching the cave, they spot a young blond guy named Wiseman already present. While trying to rescue him, they stumble upon a gateway to an alternate realm. Alas, their path is blocked by the mighty Black Knight who accuses Gash of stealing a magical book. Faced with the prospect of being stranded in the new world endlessly, Gash and Kiyomaro must track down the true culprit in 24 hours.