In the universe of Cosmic Year X492, where space travel is commonplace, a young B-Cuber video creator named Rebecca Bluegarden lands on the mechanical planet Granbell. There she meets Shiki Granbell, a human boy raised entirely by robots, who possesses the rare ability to manipulate gravity with his ether gear known as Demon Gravity. Shiki has been taught by the machines, particularly his adoptive grandfather known as the Demon King Ziggy, that friends are the most precious treasure in the universe. After befriending Rebecca and her cat-like robotic companion Happy, Shiki decides to leave his home planet for the first time, embarking on an adventure through the cosmos aboard Rebecca’s ship, which is later revealed to be the legendary EDENS ZERO. Their primary goal is to find Mother, a mythical goddess said to reside at the edges of the universe.

The main crew of the EDENS ZERO expands to include Weisz Steiner, a genius engineer who can manipulate machinery with his Machina Maker ether gear, and Homura Kogetsu, a skilled swordsman who wields the Soul Blade ether gear and is the disciple of the legendary Valkyrie, one of the Demon King’s Four Shining Stars. The story is set across a vast and colorful galaxy filled with diverse planets, from the digital nightmare of Digitalis to the sunlit waters of the planet Blue Garden. The narrative explores complex themes such as the nature of humanity, the value of memories, and the consequences of time manipulation.

A major narrative arc begins on the planet Norma, where the crew encounters a temporal paradox that introduces the concept of parallel worlds. This is followed by the Belial Gore arc, where the group confronts the criminal kingpin Drakken Joe, a fight that forces Rebecca to unconsciously awaken her true ether gear, Cat Leaper, which allows her to leap between timelines. This power reveals that the universe has already been rewritten multiple times. The series culminates in the Aoi Cosmos and Nero 66 arcs, a massive interstellar war where Shiki faces Poseidon Nero and his ruthless son, Shura. The conflict results in the devastating Aoi War, which concludes with the destruction of a major planet and Shiki losing his left eye, later replaced by a mechanical one.

Three years after the Aoi War, the story jumps forward to show a more mature crew still battling against the return of the true Demon King, Ziggy, who has become the main antagonist. The narrative moves towards its conclusion on the planet Lendard, where Shiki learns the cyclical truth about Ziggy and the fate of the universe. The final arc sees the crew using the EDENS ZERO’s ultimate power to travel to Universe 0, the original timeline. In this final world, Shiki reunites with his past, and the crew confronts the final villain, the Chronophage, as they race to save their home worlds and reach Mother.