WARNING: The following contains spoilers for Bleach: Can’t Fear Your Own World, available in English from Viz Media in July.
Shūhei Hisagi’s original Shikai is nothing special. Despite the ninth squad lieutenant having proficiency with the weapon, its abilities largely pale in comparison to those of other Shinigami. This is why his captain, Kensei Muguruma, urges him to achieve Bankai. In the penultimate chapter of the Bleach manga, Shūhei claims to have acquired Bankai through training with Kensei, but is roasted by Toshiro, Rangiku and even Kensei himself, who dismiss his claim because, like us, they had yet to see him use it.
Luckily for Shūhei, and us, Ryohgo Nartia’s canonical Can’t Fear Your Own World light novel series (a prequel to the last two chapters of Bleach) reveals that the Shinigami wasn’t bluffing. Here’s a breakdown of Shūhei, his Zanpakutō Kazeshini, its original Shikai, true Shikai and Bankai releases.
Kazeshini’s Shikai command is “reap” and, appropriately, upon utterance Kazeshini transforms from a basic katana into two twin-bladed kusarigama. One of the blades on each kusarigama is inverted, and the two weapons are tethered together via a chain. This chain grants Shūhei extended range when using the two blades as retractable projectiles, and can also be used to spin the kusarigama around when launching a fan blade attack. The chains can also be used to immobilize opponents.
Despite Shūhei’s role as a Shinigami, he dislikes killing, leading him to abhor the shape of Kazeshini in its released state as it resembles a tool “designed to take lives.” And herein lies Shūhei Hisagi’s inability to access Kazeshini’s true power; Shūhei completely misunderstands himself, and thus Kazeshini.
In the Can’t Fear Your Own World novels, Shūhei takes it upon himself to save the misguided Hikone Ubuginu, an extremely young Arrancar with immense power. When the Gotei 13 confront Hikone, Shūhei requests that his colleagues stand down, and allow him to deal with the child as he intends to “stop” the boy rather than kill him. Shūhei urges Hikone to use his immense power to take control of his own life and face his fears born from the world around him. Hikone, refusing to listen, simply notes the gap in their power and cuts Shūhei in half.
Shūhei is then transported to his inner-soul and engages in a conversation with Kazeshini’s manifested spirit. Kazeshini states that as he is Shūhei’s shadow; Shūhei himself is the one responsible for his shape. Shūhei wanted to become a Shinigami, a God of death, despite fearing and rejecting the concept of death. This leads to Kazeshini, as a weapon, developing a one-sided nature, only capable of taking life. Kazeshini happily remarks that Shūhei, having accepted death in an attempt to save Hikone, has rid himself, and thus Kazeshini, of contradiction. The sacrifice of his own life meant that Shūhei had willingly faced his fear of death, granting him an understanding of the concept that is no longer one-sided, allowing him to fully submit to Kazeshini and Kazeshini to him.
Following this conversation, Hikone is restrained by Kazeshini’s chains and met by a completely revived Shūhei. Hikone removes the chains and cuts Shūhei’s body in half once more, but is surprised to see Shūhei completely heal again. This series repeats itself until Hikone notices that the healed wounds are being closed and sewn back together by chains, the same chains used to tether Kazeshini’s twin kusarigama. This is Kazeshini’s true Shikai ability — Kazeshini’s chains revive Hisagi infinitely, completely reattaching any severed body part and sewing together any wound. This ability is seemingly limitless as Hisagi can survive complete destruction of his heart and even his Saketsu, the source of a Shinigami’s power.
Following another repetitive string of bisections and revivals, Shūhei utters “Kazeshini Fushi no Kōjyō” (Undying Hangman’s Noose), his Bankai release. Kazeshini Fushi no Kōjyō sees a giant spherical mass of chains tower above both Shūhei and his desired target. From this mass rains a seemingly infinite number of chains that surround and wrap around the necks of Shūhei and the target, tethering them both to each other and to the mass itself. Regardless of an opponent’s strength, these chains drain the Reiatsu of both parties and use it to heal any damage inflicted while they are connected to each other. Barring a premature release of the technique by Shūhei, a cycle of death and rebirth will continue infinitely until the chained parties’ combined pool of Reiatsu is drained. Kazeshini Fushi no Kōjyō is inescapable, and any attempts to flee result in the escapee forcefully being dragged back to the mass of chains.
Shūhei still possesses the twin kusarigama while in Bankai, and demonstrates free manipulation of chains born from the ability, allowing him to deal damage to opponents as he sees fit. Due to the drain of Reiatsu affecting him as well, this Bankai works best when Shūhei’s allies are nearby as it forces an infinite stalemate regardless of an opponent’s strength. Once the enemies’ Reiatsu runs dry, it gives his teammates the opportunity to capture the enemy or finish the job.
Shūhei originally misunderstood Kazeshini, as its true shape is a combination of the blades that bring death as well as the chains of life that bind these blades. Kazeshini Fushi no Kōjyō represents the stagnation of the cycle of life and death, as through continuous revival — and thus, life — it denies both its user and their opponent death. The abilities of Kazeshini’s true Shikai and Bankai also represent the duality of Shūhei: a Shinigami obligated to take life while simultaneously valuing it. Shūhei states that this ability is perfect for him, and we’d be hard-pressed not to agree.
The potential of Shūhei Hisagi's Zanpakuto was only fully awakened in the spinoff Bleach light novels.