Rei, Nico’s most constant shadow, operates in daylight as a personal caretaker and executive bodyguard, maintaining the flawless, soft-spoken veneer of a meticulous handler. In the subterranean belly of the underworld, however, he is the dreaded Rank 2 on the Ladder, his pristine silk gloves masking an execution efficiency that never leaves a trace.

In sharp contrast stands Fei, who poses publicly as a corporate assistant and personal escort. On a normal Tuesday, Fei behaves like an erratic, unhinged mad dog with zero moral impulse. Yet, the split-second he takes a contract seriously, he transitions into a terrifying anomaly revered across the underworld as the "Ascendant" (or "Xian-ren"). As Rei's lethally seasoned predecessor, Fei rules the immovable apex of Rank 1 on the Ladder through raw, terrifying kinetic dominance.

Anchoring this lethal triumvirate from the digital abyss is Kei, whose public identity is safely buried under the quiet title of an "Esports Assistant," managing Nico’s professional gaming logistics. In truth, Kei is the ghost who wrote the rules of the dark—the omniscient architect who invented and codified the entire Underworld Power Ranking System (Rank 0). As the absolute predecessor to both Rei and Fei, Kei doesn't merely analyze data; he dictates the causal algorithms of life and death, serving as the silent, unshakeable trump card in Nico's hands.