The events take place in the vibrant yet dilapidated underground city of Lux. Denizens of Lux have come to call it "The City" and treat it as a sentient force. Three factions vie for control of the city: the Organo, a strictly professional conglomerate with ties to the criminal underworld in the prosthetics business ("Texhnolyze"); the Union, a fanatical populist group interfering with Organo's affairs; and Racan, a marauding group of Texhnolyzed youths. The series has an ensemble cast, but events particularly focus on Ichise, a stoic prize fighter who loses a leg and an arm to satisfy an enraged promoter; Onishi, a young but level-headed executive of the Organo who has many enemies; and Ran, a little girl who has a very important gift that affects the entire city. As they struggle to accept the challenges that they are dealt, the characters bear witness to major events that determine whether the city continues to exist.