Zanpakutō Spirit Manifestation

When Muramasa forces a spirit into the open, the result depends on the Shinigami it comes from. A weaker soul yields little more than a tangible shadow, while a stronger one produces a spirit of clear individuality and power. A spirit drawn out inside its inner world first appears draped in a black cloak that then crumbles away.

Muramasa enters a Shinigami's inner world and turns their spirit against them by breaking the energy stability between the two and forcibly venting the spirit's negative emotions, a kind of brainwashing. A victim in this state cannot release their Shikai until they harden their resolve, and cannot use Bankai at all until the spirit is returned. He has several methods: flooding an area with purple energy from his eyes to release many spirits at once, reaching into a chest to pull out a thread of Reiatsu, or trapping the Shinigami in an illusion of spiritual threads until their will breaks. Freedom comes only when the rightful owner defeats their own spirit; if anyone else strikes it down, the sword reverts and snaps, effectively killing the spirit, though Mayuri Kurotsuchi later devises a way to restore them. Resisting the power at all requires having felt it before and knowing Muramasa's voice.

Muramasa deploys this ability across the anime-original Zanpakutō rebellion. Once his master Kōga was sealed away, he could no longer hold his own form and began absorbing Hollows to prolong his time in the real world. Spirits left masterless without being subdued turn berserk from the loss of their identity, beings Kurotsuchi labels Tōjū, and Yamamoto compares the whole affliction to a tapeworm.