20th Century Boy

20th Century Boy belongs to Magent Magent and features in Steel Ball Run as a hollow suit of beetle-shaped armor, built from a headpiece, broad shoulder pads trailing branching straps, and a back shell. It carries no meaningful attack, ranking Null in both destructive force and range, but trades away almost everything else for a peerless defense and pure survivability. The Stand is also flexible enough to change shape, and the colored manga renders it in purple and cyan.

The Stand's signature power is a flawless defense. The moment Magent activates it and drops to his knees, every incoming threat is turned aside. Araki described the mechanism as belts that stretch out like grounding wires, channeling the force of any strike harmlessly into the earth. This shields him from Stand blows, thrown Steel Balls, bullets, and explosions alike, and even keeps him safe from hazards such as drowning. It first stops Gyro Zeppeli's Steel Balls and later deflects a bullet already breaking the skin of its user's face.

The catch lies in how the guard is raised. Magent has to expose himself or hold perfectly rigid to invoke it, so the defense breeds its own weakness. Opponents can bait him into lowering his guard for a sneak attack he cannot react to in time, or take advantage of his forced stillness to bind him in a hopeless situation.

Magent Magent is the sole wielder. The Stand's name mirrors his character, especially his constant longing for modern devices like airplanes, machines of the twentieth century that he imagines would make his work far easier.