One, also known as King or King of the Jar, leads the Eighth clan in Darwin's Game, ruling Shibuya territory through ruthless intimidation and violence rather than strategy. His leadership thrives on inflicting prolonged suffering via torture, emphasizing psychological dominance over opponents.

His Sigil enables spatial manipulation with three distinct powers: standard teleportation within 5 meters (extendable to 10 meters via concentration, with rare panic-driven leaps exceeding 100 meters), precision cutting within 1 meter that ignores conventional durability, and position-swapping with targets under 10 meters away. These abilities make him lethal in close combat, where he prioritizes evasion through rapid teleportation and maximizes pain by methodically dismembering adversaries.

During Shibuya's Treasure Hunt event, Kaname Sudo claims a treasure intended for One. Viewing this as a personal humiliation, One retaliates by kidnapping, torturing, and killing Kaname's friend Yota Shinozuka. This act drives Kaname and the Sunset Ravens clan to target One and the Eighth clan, culminating in the Eighth's total annihilation by the Sunset Ravens. This conflict ends One's reign and eliminates him from the game.