A solar flare has awakened Spark Dolls from the depths of the earth and the ocean, materializing them into rampaging monsters that terrorize the Earth. Due to this, a new attack team was formed, Xio (Stands for Xeno Invasion Outcutters) to combat the threats. Fifteen years later, Xio member Daichi Ozora bonds and transforms into Ultraman X to battle threats from both aliens and monsters.