A Holder (ホルダー Horudā?) is a unique robotic animal that carries a variety of uses and classes ranging from pet, battle unit, or even service robot.
When a Samurai gets the the Handle Bone from a Holder, that Holder becomes the Samurai's Key Holder (キーホルダー Kī Horudā?). Each Samurai possess a companion Holder that carries the Samurai Armor of the samurai as an outer skin. When the armor is summoned by the samurai, they remain in a skeletal form. Samurai can also ride on top of them for transportation purposes. Samurais can have one Handle Bone in each forearm and can possesses more than a Key Holder from differents ranks.
*There is five ranks in Japanese Sumo. From the lowest to highest: Maegashira (前頭), Komusubi (小結), Sekiwake (関脇), Ôzeki (大関) and Yokozuna (横綱). There is a chance that Holders can be in this rank too.