The Youkai are a race in the Guilty Gear series. Youkai and Gears are very similar in construction: both are infused with magic and animal DNA, and often bear human traits (or in a Gear's case, human DNA). The only difference between Gears and Youkai is that Youkai are beings born within parts of the Backyard, whereas Gears are artificially created to serve humans and function according to a system of commands. Even the level of growth and adaptivity, as well as development of self-awareness between Gears (Gears that are free from Justice's commands) and Youkai is identical. Even more, Youkai can easily be manipulated by a Command-Type Gear's song (namely Justice) alongside the Gears themselves, thus establishing a link between Youkai and Gears. Izuna and his servants are examples of Youkai. It could even be said that Youkai are the natural predecessors of Gears.