Chatan and his family went to their grandfather's house for a vacation! He spends a pleasant time with his new friend that he met there, Sam-soon. At that time, an incident occurs where the luxury watermelons raised by her grandfather disappeared. The culprit is a mysterious magician located in the village? What they are looking for is watermelon energy! Chatan, Carbot, and their new friend, Sam-soon, will face off against a mysterious magic gang that seeks to conquer the earth! Stronger with the legendary Pentastorm X! They're back, and more splendid!