Zanpakutō Spirit Manifestation

 is a technique used by the manifested spirit of Kōga Kuchiki's Zanpakutō, Muramasa.

Description
Zanpakutō Spirit Manifestation: Muramasa can enter the inner world of a Shinigami and bend their Zanpakutō spirit to his will. This is done by removing the energy stability between a Shinigami and their Zanpakutō spirit, who is left confused and has its negative emotions forcibly released by Muramasa. A manifested spirit of a weaker Shinigami is typically a tangible, shadowy figure, but manifests with greater individuality and power from stronger Shinigami. Initially, a Shinigami whose Zanpakutō spirit has been manifested is left unable to release their Shikai, though they can overcome this by strengthening their resolve. However, as long as their Zanpakutō spirit is manifested and under the influence of Muramasa's brainwashing, a Shinigami cannot perform Bankai until their Zanpakutō spirit returns to them. The only way for a manifested Zanpakutō spirit to be freed from Muramasa's brainwashing and return to its Shinigami is for its owner to defeat it. However, if someone other than the manifested Zanpakutō spirit's owner defeats them, they will revert to their sword form, which will snap in two afterward, and remain unable to manifest, effectively dying, though Mayuri Kurotsuchi eventually discovers a way to restore the Zanpakutō spirits who were defeated in this way. Genryūsai Shigekuni Yamamoto likens this power to a tapeworm. The only way for a Zanpakutō spirit to resist this power is to have experienced it before and know Muramasa's voice, allowing them to resist its influence. Additionally, Muramasa can use this power to manifest himself into the real world, which he did in order to rescue Kōga Kuchiki.


 * Methods: Though he can manifest several Zanpakutō spirits at once by emitting purple energy from his eyes, which causes nearby Zanpakutō to glow blue and release their spirits, Muramasa can also personally draw out a Zanpakutō spirit from a Shinigami by reaching into their chest and pulling out a thread of their Reiatsu while speaking directly to the Zanpakutō spirit in question, after which the Zanpakutō spirit will manifest in the real world. This process will cause a Shinigami wielding their Bankai to instantly revert to their Shikai. Additionally, while inside the inner world of a Shinigami, Muramasa can draw out their Zanpakutō spirit by trapping the Shinigami within an illusion in which they see Muramasa's Spiritual Threads extending from a hole in their chest. When the Shinigami's resolve breaks from the perceived pain of this illusion, their Zanpakutō spirit will manifest within their inner world while wearing a black cloak, which crumbles away. After this, Muramasa can proceed with brainwashing the Zanpakutō spirit. The latter two methods are both very painful to the Shinigami in question.