Sankishin Zanpakuto

Overview
A term used by Tazuma, which he uses to classify Zanpakuto whom were born or forged without having an initial Master.

How Sankishin are birthed
Tazuma, trained in the art of repairing and even creating Zanpakuto, surmises that there are two known methods that a Sankishin Zanpakuto are birthed into existence:
 * The first is that a Zanpakuto is forged by constantly tempering an Asauchi, a method Tazuma uses to forge new Zanpakuto.
 * A rouge manifested Asauchi is exposed to outside stimulus( such as encountering a Hollow or a Kūkyo māku and absorbs its traits, instigating an evolution into a Zanpakuto. According to Tazuma, the case this were to happen was nearly 10%. The Hollow, which was created by , due to its composition being akin to an Asauchi, is the closet thing to exist as a Sankishin. However, as it evolved into a Hollow rather than a Zanpakuto spirit, is considered to be a Failed Sankishin.

Notable Sankishin

 * Murakumo (spirit)
 * Totsuka (Spirit)
 * Tanin