Muramasa

Muramasa speaks calmly and seldom displays anger, even while declaring war on the Shinigami. He presents himself as a liberator who will free Zanpakutō spirits from servitude, exploiting their dissatisfaction with their wielders to secure their cooperation.

Beneath that rhetoric, he is single-mindedly devoted to Kōga. Centuries of separation have weakened his body and distorted that devotion into obsession, leaving him willing to manipulate other spirits and endanger Soul Society to recover his master.

Muramasa can enter a Shinigami’s inner world and appeal directly to the resident Zanpakutō spirit. His influence separates the spirit from its wielder, suppresses the Shinigami’s access to the weapon and gives the manifested spirit an independent body. A spirit that recognizes his voice and has already overcome the effect can resist it.

He also creates nearly invisible spiritual threads that bind or strangle targets; the threads can be seen in reflections and disrupted by disturbing the reflected image. Muramasa produces sensory illusions from a victim’s memories, opens Garganta and fights effectively with a sword.

His deteriorating body consumes Hollows to sustain itself. This temporarily increases his strength but gradually contaminates him, eventually producing a monstrous Hollow-like transformation.

Muramasa gathers the manifested Zanpakutō spirits and leads an assault on the Seireitei. Although he claims to seek their freedom, his actual objective is to penetrate the barrier surrounding Genryūsai Shigekuni Yamamoto, use Ryūjin Jakka to break Kōga’s seal and reunite with his master.

Kōga reveals that he called for Muramasa while being sealed but was never heard. Believing his Zanpakutō abandoned him, Kōga rejects and impales the spirit. Muramasa nevertheless defends him until Kōga is killed, after which accumulated Hollow corruption overwhelms Muramasa. Ichigo ultimately destroys his transformed body.

Kōga Kuchiki is Muramasa’s master and the focus of his centuries-long devotion. Their inability to hear one another during Kōga’s sealing turns their bond into mutual resentment and tragedy.

Ichigo Kurosaki repeatedly opposes Muramasa and ultimately defeats him. Byakuya Kuchiki infiltrates the rebellion while pursuing Kōga, and Genryūsai Shigekuni Yamamoto maintains the seal Muramasa seeks to break.