In the far future, a huge mass of energy suddenly appears near Mars, which causes unusual natural phenomena. As a result, wars and terrorism occur all over the world. The Earth only has a hundred years left because of the damage. In order to avoid extinction, mankind creates two plans to escape from Earth. One is to form the World Integrated Government to gather resources and suppress antis. The other is called the "Felix plan". Humans need new technologies to travel to outer space and migrate to other planets, so they create a new species called Felix by manipulating genes. Felix are humans with high intelligence and immortal bodies. Ninety-nine years later, a Felix girl named Sion who devotes her whole life to humans' plans has accomplished all her tasks and decides to stay on Earth for the rest of her life. Then a boy, Ryō Haruna, is sent to protect her, as well as restrict her freedom.
Source: Wikipedia, "Eden*", available under the CC-BY-SA License.