The United Earth Sphere Alliance is a powerful military organization that has ruled over Earth and space colonies with an iron fist for several decades. When the colonies proclaimed their opposition to this, their leader was assassinated. Now, in the year After Colony 195, bitter colonial rebels have launched "Operation Meteor," sending five powerful mobile suits to Earth for vengeance. Built out of virtually indestructible material called Gundanium Alloy, these "Gundams" begin an assault against the Alliance and its sub organization OZ. One Gundam, whose pilot has taken the name of the slain colony leader Heero Yuy, is forced to make a crash landing into the ocean after an atmospheric battle against OZ's ace pilot Zechs Marquise. Upon coming ashore, he is found by Relena Peacecraft, daughter of a peace-seeking politician, who witnesses Heero's descent to Earth. Although neither of them realize it yet, this encounter will have a profound impact on both their lives, as well as those on Earth and in space colonies. [Written by MAL Rewrite]

After the decline of the once robust fields of science and technology, a new energy source known as magic fuels the modern era. Humanity creates forbidden biological weapons: Gears. Those Gears eventually stand against humanity in a rebellion. Although they manage to overcome in the struggle for survival known as the Crusades, humanity's losses are so great that even after several decades pass, their emotional wounds remain unable to fully heal. Sin Kiske, the child of a human and a Gear, heads to his father Ky and mother Dizzy's wedding ceremony. Their wedding breaks the ultimate taboo: a union between a human and a Gear. Even with the world at peace, it took many years for such a ceremony to come to fruition. Despite the complex array of emotions surrounding it, the wedding ceremony is met with blessings. When suddenly, a mysterious girl appears... The fated child inheriting Gear blood–and the mysterious girl who despises Gears. Their meeting would shake the world.

Kimihiro Watanuki can see spirits and other assorted supernatural creatures, which is quite a bothersome ability he strongly dislikes. On the way home one day, while plagued by some spirits, he is inexplicably compelled to enter a strange house. There, he encounters Yuuko, a mysterious woman who claims to be able to rid him of the ability to see and attract the troublesome creatures—for a price. She demands that he work at her "store" that grants wishes to people, and thus begins Watanuki's adventures through weird and wonderful events. [Written by MAL Rewrite]