In "Blow Up," the battle between the Knight Sabers and Genom (personified by the evil Mason), comes to its inevitable conclusion. Or so it seems...

Part 1 introduced us to a future Tokyo. A huge shadow, Genom, looms over the megalopolis, which, like today, contains endless contradictions, distortions, corruption, and decadence. Genom is a symbol for our worst fears, typified by the Boomers (artificial humans) it produces.

Mason is the man who directs the seamy side of Genom. In Part 1, he appears as the mastermind behind Cynthia's kidnapping, and as a confidant of Quincy, the man who rules Genom. In Part 2, he gives a glimpse of his ambitions: he is not content with being a prince. His Super-Boomer project ends in failure, however, when Irene's murder spurs the Knight Sabers into action. In Part 3, Mason's ambition sets him upon a path from which there is no turning back. Who is Mason? And why has he turned Megalocity Tokyo into a battlefield?

In response to the frequent Boomer riots, AD Police retaliates by deploying its K-11 armored suits, but with only army-issue machine guns, the K-11's are no match for a Boomer with genuine firepower. The street fighting between ADP and the Boomer throws Tokyo into a panic, and the damage extends from the slum where Priss resides to the area where Sylia's fashion building (and the Knight Saber's secret headquarters) is located.

Recognizing that the night's events were clearly instigated, not merely by Genom, but by Mason, Priss advocates a counter attack. As usual, Sylia vetoes precipitous action. Though not pacified, Priss finds a new outlet for her determination when Mackie shows her the newly powered-up Motoslave. Her dark mood is also lightened by the friendship of a young boy, Sho, and his mother.

Meanwhile, computers at Genom and in Sylia's back room are humming as both Mason and Sylia plot their next moves.

A few days later, Mason and his Boomer bodyguard, Funk, arrive in the slum with a little urban renewal on their minds. Aided by some well placed bribes, they plan to level the tenements and replace them with an industrial complex. Priss makes a futile attempt to intervene, and is rescued by Leon, who does little to improve his standing in her eyes by trying to pick her up.

When Sho's home is demolished, and his mother is killed in the building's collapse, Priss finally explodes. Disregarding the Knight Saber rule against solo action, she prepares to challenge Mason. The other Knight Sabers, having heard of the death of Sho's mother, are already suited up, waiting for her.

Thus the Knight Sabers and Mason head straight for a showdown. The time has come to decide who will triumph. Mason, garbed in the latest personal armor, awaits the Knight Sabers atop the summit of Genom's pyramid-like headquarters, a modern Tower of Babel rising above Megalocity. The Knight Sabers race towards him on their new Motoslaves. The battle reaches the apex, and Sylia and Mason finally confront each other; a meeting that only one of them will survive.