Kazeshini (Zanpakutō spirit)

Kazeshini takes shape as a lean, well-muscled dark-skinned man with pale blue eyes and black hair spilling down to his lower back. Grey strips of cloth wrap his neck, shoulders, wrists, and lower body, and curl-toed grey boots finish the look. A faintly flickering red outline traces his frame, and pronounced canine fangs lend his grin a savage edge.

Driven by Muramasa's brainwashing, Kazeshini is cocky, impulsive, and prone to wild laughter, boasting that he could face the whole Gotei 13 single-handed. He proclaims that reaping lives is his one and only purpose and fights without mercy or scruple, cutting down weaker foes and sneering at any spirit beaten by a Shinigami. His bond with Hisagi is openly hostile; he belittles his master and insists reaping was the only thing he ever owed their partnership. Even after the brainwashing lifts he keeps hunting Hisagi, until minding an orphaned baby against his will thaws him, teaching him the worth of protecting others and turning him toward making amends.

In the Zanpakuto Rebellion, Kazeshini joins Muramasa's uprising, slaughtering Shinigami during the assault on the Seireitei and ambushing fighters like Renji and Rukia. He battles Hisagi to a draw before Izuru Kira intervenes, later loses to Izuru, and is finally beaten by Ichigo, breaking back to blade form. In the follow-up Beast Swords arc he alone keeps attacking Hisagi rather than returning to the sword, but caring for a dying man's baby changes him: he shields the child, faces Hisagi in a fair fight, and accepts a shared purpose of guarding others. He later helps the spirits against the energy-draining Kirikaze before his materialized form finally gives out and he returns for good to Hisagi's blade. In combat he relies on twin kusarigama, wind-like shadow blades, and a spinning tornado transformation.