Goro Numata (沼田 五郎 Numata Gorō) or Kikkaijin Spark (奇械人スパーク Kikkaijin Supāku) is a disused Kikkaijin after an unsuccessful operation. He was Shigeru Jo's best friend and the basic prototype of Kamen Rider Stronger. In the manga Kamen Rider Spirits, he was resurrected by Badan Empire, but later Shigeru killed him and harried Spark's components. These components helped Shigeru to transform into Stronger again.