Bound spirit

Bound spirits are spirits of departed mortals that have been summoned back to the mortal world and bound in a physical shell called a construct to the service of their master.

Shiro Tagachi abuses his power as an Envoy (which gives him great powers over the souls of the dead) and binds spirits to his evil bidding. This is done through the use of spirit binders, constructs devised by Shiro. The spirit binder provides the spirits with a mortal body to fight in while Shiro's power binds them to his service. For this, they are called the Shiro'ken. The Shiro'ken are animated through the use of Soul Stones.

Shiro'ken are not the only things that contain a bound spirit. Any being that contains a soul does this, such as the Kurzick Juggernauts, however it is unclear as what contains a bound spirit.