Karoshi as he appears in Rise of Golden Power.
Karoshi is an electric-variant Ekyra, abandoned in infancy by Hizoker and left to be raised by the Dot population of Centro City. With no parents or relations to his name, he, Shadden, and Litek are the only remaining Ekyra by the time of Karoshi's Shadow.
Karoshi later gains a brother in the form of Ihsorak, who is cloned from him at the very end of the Cobran arc. Another evil Ihsorak as well as Enigma's creation, Sikorah, complete the set of blood relations to Karoshi.