Empty Void

In his monstrous state, Void's skin bristles with spikes, ridged lines stand in for hair, his eyes turn animalistic with black sclera, and every tooth sharpens to a point. His human form is lean yet muscled, marked most notably by a V-shaped scar on his forehead. He keeps his rough, pale hair long and gathered into a ponytail, styled toward the front much like Blast's. Goggles, a scarf, and wrapped cloth sit over layered plating that guards his arms, shoulders, chest, and back, with small pouches at his waist and two sheathed katanas crossed behind him.

Under "God's" sway, Void served without question, putting countless Ninja Village recruits through brutal trials to weed out candidates fit to receive the entity's power. Once Saitama's blow shattered that hold and restored his humanity, his self-awareness came flooding back. He recalls every act committed while enthralled, describing the ordeal as his own flaws magnified, and he regrets having distrusted Blast and stumbled into the trap laid for him. Though he wishes to make amends to the Heavenly Ninja Party for their suffering, he places rejoining Blast's fight above all else. The webcomic paints an even darker figure: a cunning, bloodthirsty killer of more than three centuries who slaughtered untold thousands and stripped the bodies of strong victims to keep himself young.

Void came up inside an assassin school much like the one he would later build, an organization whose graduates turned on one another in a scramble for power until he alone was left standing. He rose to become the deadliest ninja in recorded history, blamed for the deaths of numerous prominent figures and credited with a body count in the six figures. At some point he established the Ninja Village, then allied with Blast and a circle of collaborators to hunt the mysterious cubes, objects capable of warping humans into monsters and even opening a channel to "God." Because he acted rashly and refused to trust Blast, Void fell into a trap, accepted power from the entity, and became a Mysterious Being. Blast defeated him in the resulting duel, and the wounded Void retreated into a recovery capsule hidden behind a barrier that kept even his former partner from finding him. Years later, Speed-o'-Sound Sonic and Flashy Flash stumbled onto him lying dormant in that chamber, a cube enshrined beside him.

During the Ninjas Arc, the Heavenly Ninja Party, a band of elite Ninja Village graduates, tells Sonic that their master, whom they call "That Man," has awoken and means to kill Flashy Flash and Blast before seizing the world through superior ninjutsu. After the party's clash with Sonic and Flash, Blast teleports everyone to Sonic's hideout, where they find Saitama seated beside a body-shaped crater. Saitama explains that Void attacked him and dropped to a single punch. Moments later a rift tears open in the sky because Blast has strayed too far from his post, and the divine beasts Byakko and Genbu burst through, unleashing devastation that Blast blocks with a barrier. The revived Void cleaves both beasts apart with his Dimension Slash, Blast finishes them with his Giga Gravity Blow, and as the threat passes Void's monstrous face splits away to reveal the human beneath, freed at last from "God's" grip.

Sonic and Flash immediately strike at him, but he brushes them off, and Blast clarifies that Void only tormented them at the village while under the entity's control. Admitting he remembers everything and regretting his distrust of Blast, Void resolves to return to the front line against "God" and vows to settle his debts to the ninjas later. He and Blast then leap through a portal to the Rift in Spacetime, where they find the corpses of Byakko and Genbu beside Kirin, another beast felled by Saitama. As the strongest ninja ever to live, Void wields overwhelming strength and speed; he split two divine beasts ranked above Dragon level and held off both Flash and Sonic at once. His command of ninjutsu spans a concealment barrier able to hide the entire village, the space-cleaving Dimension Slash delivered through his twin swords, and further forbidden arts recorded in scrolls he carried, one of which Flash later used to slay the Dragon-level Heavy Smoker.