Loco

Loco is the strongest Rook and one of the first Chess Pieces introduced. Loco's name means a patron of healers in the religion of Voodoo, a reference to her ÄRM Straw Doll (Spikes and Hammer). Loco was born 32 years before the main part of the series. At age 26, Loco, at that point a Pawn, the lowest Chess Piece rank, was given the order to participate in the attacking of a, unknown, town. While fighting, Loco's only ÄRM the Weapon ÄRM Ring Dagger, was broken, leaving Loco defenseless. While stumbling throughout the battling village, Loco crossed paths with a midget-like cloaked figure carrying a large suitcase.

The cloaked person asked Loco if she wanted strength, to which she answered that she only wanted power to fight with. The cloaked person then gave Loco the suitcase, telling her it was full of seven Darkness ÄRMs, the cost of using being reversed aging, and the mysterious figure died from the ARM's effects. Using the Darkness ÄRMs, Loco eventually increased in the ranking system to the strongest of the Rooks. The Darkness ÄRMs affects had damaged her, however, as her body had been transformed into a young child's by the series' beginning.