It is Universal Century 0079, at the end of the One Year War between the Earth Federation and the Principality of Zeon. The space colonies of Side 4, or Moore, were previously destroyed by a Zeon attack, and many colonists lost their lives. Side 4 became a shoal zone filled with the wreckage of destroyed colonies and warships, lit by constant flashes of lightning due to collisions between electrified debris. It soon came to be known as the "Thunderbolt Sector.
The Moore Brotherhood, an Earth Federation Forces unit made up of surviving citizens from Moore, set out to exterminate the Zeon forces in the Thunderbolt Sector in order to reclaim their homeland. To halt the Federation advance, the Zeon forces deployed their own Living Dead Division, which was established to collect combat data on soldiers with prosthetic limbs
Io Fleming, though part of the Moore Brotherhood, hates being tied down by his homeland and family history. Daryl Lorenz, having lost his legs in earlier battles, is now an ace sniper of the Living Dead Division.
When they confront each other on the battlefield, they will reach a mutual realization.
These two are destined to kill each other
This appears to be a manga adaptation of the 2014 film, Appleseed Alpha, which seems to be an alternate telling of the main characters' origins. In the world of Appleseed, a third world war has left the world in ruins. This alternate story begins with Deunan Knute and Briareos traveling together as lovers, with Briareos already as a full cyborg. They arrive at the ruins of NYC, where they meet the local leader, Two-Horns, who gets them involved in the local situation. [tethysdust
World War III is over, and nomad soldier Duenan Knute and her cyborg partner Briareos struggle to survive in the abandoned cities and demilitarized zones of the post-war wasteland, the "Badside." Matters appear on the upswing, however, when they are found and brought to Olympus, an urban utopia and centerpiece for the reconstruction of civilization. Duenan and Bri join the Olympus police, a force that seems hardly necessary in such a paradise. But, like in most pretty pictures, perfection is an illusion, and Olympus's peaceful facade hides a dark secret, a violent struggle between human and cyborg that could once again plunge the world into war... and genocide
Note: Won the Seiun Award for Best Manga in 1986