A newly moved little girl named Sakura befriends Pigmon, a small monster that had been dubbed as a ghost by several villagers and had played with children over the past years. While Sakura and her friends are at the shopping complex, Pigmon appears to warn everyone of the Dark Thunder Energy but the civilians mistook Pigmon for a hostile monster, catching it until Xio arrives and the Dark Thunder Energy summons King Guesra. King Guesra was purified and defeated by Ultraman X, turning into Spark Doll but Pigmon seemingly died after saving a man from a falling rubble. The next day, Pigmon was revealed to have survived and nurse back to health by Xio members before releasing it to Sakura.