The year is 1863 and as Japan's long festering wounds of political discord erupt into violent waves of street clashes and murder, the Tokugawa Shogunate sends a new force of masterless samurai called the Roshigumi to the aid of the Aizu forces in Kyoto. However the new "police" are anything but a cohesive force and assassination has already split them into two opposing factions. The stronger is led by the brutal Serizawa Kamo and the lesser by the more honorable but less assertive Isami Kondo. It is into this pack of wolves that Ryunosuke Ibuki is dragged by the rabid Serizawa. Forced to be a virtual slave by blood debt, he hates the samurai and everything they stand for. But as he sees how the other half of the samurai live, he begins to believe that there may still be a chance, for both himself and Japan, if only Kondo will step up and take down the mad dog Serizawa!

In 2038, Yuuma Sawatari is an elementary school kid who loves everything about space and astronomy. He was initially excited when his parents bought a robot called Nanako, but he was disappointed when he learned that she was basically just a boring housekeeping robot. However, when he does finally try to talk to her about space, something strange happens. Her system crashes and is taken over by what claims to be a marooned alien ship! The alien ship wants Yuuma's help to get back to space!

In the distant future, trains are no longer bound by their physical tracks. Instead, they take to the skies and travel across the universe on the Galaxy Railways, transporting mankind from planet to planet. However, the Galaxy Railways are no safer than traditional trains: criminals, terrorists, and vile aliens always find a way to stir up trouble. Manabu Yuuki, a rash and hot-headed man, is the latest addition to the Galaxy Railways' elite Space Defence Force (SDF). These brave men and women are responsible for protecting the railways and responding to any unprecedented danger, risking their lives to protect the innocent from evil. But as this drama unfolds and the SDF's greatest crisis draws nearer, Manabu must truly learn what it means to be a member of the SDF before it is too late.

On November 22, 2010, Japan was hit by missile strikes, a terrorist act that fortunately did not harm anyone, becoming known as "Careless Monday." Quickly forgotten, society goes on about their lives as normal. During her graduation trip to America three months later, friendly college student Saki Morimi's life is forever changed when she finds herself saved from unexpected trouble by Akira Takizawa. Takizawa is cheerful, but odd in many ways—he is stark naked and suffers from amnesia, believing himself to be a terrorist. In addition, he possesses a strange cell phone loaded with 8.2 billion yen in digital cash. Despite Takizawa's suspicious traits, Saki quickly befriends the enigmatic young man. However, unbeknownst to her, this is the beginning of a thrilling death game involving money, cell phones, and the salvation of the world. Higashi no Eden chronicles Saki's struggle to unravel the mysteries behind her savior, while Takizawa himself battles other individuals armed with similar cell phones and returning memories which reveal his possible connection to the event from months ago. [Written by MAL Rewrite]