- Scub Coral
- Eureka Seven takes place in the year 12005 and it's now been 10,000 years after humanity has made a mass exodus into space, due to the arrival of the Scub Coral (スカブ・コーラル Sukabu Kōraru), an intelligent, sentient life who merged with the planet, forcing the humans to abandon it. In the current timeline, the remnants of humanity are now settled on an unknown planet (actually a terraformed Earth) known as the Land of Kanan, but the majority of the surface of this planet is now covered by a rock-like surface formed by the Scub Coral. The Scub Coral inhabited the Planet until the return of humans. The theory that the Scub Coral is an intelligent life form was proposed by the scientist Adroc Thurston, who also claimed the Scub is looking for mutual co-existence with humanity. All theories and information about the Scub Coral being a sentient being are kept from the general population. In addition to being the surface of the planet, the Scub Coral has several physical manifestations, called Coralians (コーラリアン Kōrarian), that are observed throughout the series. These manifestations are either natural occurrences or a response to attacks from humans. The manifestations are:
- Command Cluster Coralian
- The Command Cluster is a large concentration of the Scub Coral which acts as the central mind for the rest of its "body". It stores all the information the Scub has collected over the last 10,000 years, and keeps the rest of the Scub Coral in a dormant state.
- Kute-class Coralian
- A Kute-class is massive sphere of concentrated energy that materializes suddenly in the skies. Though it is a rare natural occurrence, they can be artificially triggered by causing heavy damage to the Scub Coral. The disappearance of a Kute causes a massive release of energy, ravaging the surrounding landscape and lowering the Trapar count in the area to almost non-existent levels.
- Antibody Coralians
- Antibody Coralians are, as the name suggests, creatures created by the Scub Coral to destroy anything nearby that might be causing it harm. They are unleashed in massive swarms through a Kute-class Coralian when the Scub Coral is threatened or attacked. These antibodies can range in size from as small as a wheelbarrow, or as large as a bomber plane. Their shapes vary wildly, from eyeballs to flying slugs to giant hovering flower-like objects. Most forms are based on the sea creatures they absorbed when they just started their 'growth'. Their powers are: sending lasers in profusion from their bodies, thus being able to destroy large aircraft, burrowing into a victim's body and imploding it (unconfirmed), and creating a spherical void, which makes anything within its surface area to vanish. Antibody Coralians generally appear in response to deliberate attacks on the Scub Coral. They appear for 1246 seconds (20 minutes 46 seconds) - which is the amount of time the Seven Swell phenomenon is active. After those 1246 seconds, they crumble to dust. Their appearances are that of basic invertebrates such as flat worms, mollusks, and cnidaria. One of each kind appears in Another Century's Episode 3: The Final and Super Robot Wars Z.
- Human-form Coralians
- Human-form Coralians are beings created by the Scub Coral in the form of humans. They are regarded by scientists as emissaries of the Scub Coral, sent to learn about humanity. Humans have attempted to create their own artificial human-form Coralians, but the results are often less than satisfactory. As shown with Eureka in the sequel series, human-form Coralians are biologically capable of reproducing the same way as humans do; she gave birth to a daughter and son. However, due to her children being Human-Coralian hybrids, the high level of Trapar would be too dangerous for them.
- Trapar waves and lifting
- In Eureka Seven, as a result of the Scub Coral covering the planet, the atmosphere is permeated by an enigmatic energy known as Transparence Light Particles (トランサパランス・ライト・パーティクル Toransaparansu Raito Pātikuru), dubbed Trapar (トラパー Torapā) waves for short. Norbu, the Vodarac leader, states that all thought carries with it energy. As a result, a sentient life form on the scale of the Scub Coral produces a tremendous amount of energy. The most important use of Trapar energy is its use as a method of propulsion for flight-capable vehicles.
- Though Trapar-propelled airships are relatively common, using Trapar waves for "lifting" (リフティング Rifutingu, or "reffing", according to some fan translations, as well as official translations in some countries) is their predominant use. Lifting uses surfboard-like devices called "reflection boards" ("ref boards" (リフボード Rifubōdo) for short) to ride Trapar waves in a manner similar to surfing, and is a popular sport in the series. The most grandiose use of Trapar—massive humanoid fightercraft—are a recent development, made possible by the discovery of bizarre alien life-forms within the Scub Coral.
The series focuses on Renton Thurston, the fourteen-year-old son of Adrock Thurston, a military researcher who died saving the world. He lives what he considers a boring life with his grandfather in a boring town. He loves lifting, a sport similar to surfing but with trapar, a substance abundant throughout the air, as the medium. He dreams of joining the renegade group Gekkostate, led by his idol Holland Novak, a legendary lifter.
An opportunity to do so literally falls into his lap when a large mechanical robot, called the Nirvash type ZERO, and Eureka, its pilot and a member of Gekkostate, crash into Renton's room. Renton's grandfather orders him to deliver a special part to the Nirvash called the "Amita Drive", which releases the immense power dormant within the type ZERO called the "Seven Swell Phenomenon". Afterwards, Renton is invited to join Gekkostate, where he quickly discovers that the behind-the-scenes life of Gekkostate is hardly as glamorous or as interesting as printed in the glossy pages of their magazine, ray=out. Only one thing makes it all worthwhile for him: the presence of Eureka, the mysterious pilot of the Nirvash. Renton, Eureka, and the Gekkostate embark on an adventure that will shape their future as well as the world's.