In the year 2187, the planet Earth, caused by global warming is leading the human civilization to certain destruction. As such people are unable to live on the Earth's surface so they created domed cities, but as time goes by, war and unstable land condition parted the dome cities and they lose contact with each other. Shuu is a teenage boy from Datania, a school-type city dome controlled by Zero, a data program, with the help of his human assistant Nines, and later Berk. They forced the children who lived there to live and work as programmed using the reset system, which resulted in the children having no emotions, needs, or human instinct, like robots. The series began when Shuu, who dreamt of seeing the ocean, escaped with his friends from Datania with the help from, Ein, May, and Dolly from The Returners, rebels of Datania who live underground. Shuu goes with the Returners to find Amaroute, another dome city which they believed to be the better place to live. Along the journey, Shuu explored the world he has never seen before, he also joined the Returners in fighting Zero and his men who are after DT, a special substance inside humans, which Shuu and his Returner friends have. Arriving in Amaroute, the Returners realized that Amaroute was the same as Datania, and likewise, it is controlled by Zero, but assisted this time, by another clone of Shuu.