Bakkōtō

Bakkōtō are a rare type of zanpakutō used by Gyōkaku Kumoi's assassins. This type of weapon differs from the zanpakutō in several ways. While the zanpakutō is a symbiotic being, working and growing more powerful as the shinigami develops a relationship with the sword's inner avatar, the bakkōtō is more of a parasite, gradually consuming the user as it did with Hanza Nukui, the now-deceased head of the Kasumiōji assassins. Also, the bakkōtō do not have any sort of known release states, instead evolving with the user's reiatsu. Finally, while zanpakutō can only be wielded by their respective Shinigami, a bakkōtō can be wielded by any person with reiatsu and varies in power and ability depending on its wielder. It is unknown how a bakkōtō is formed, however, it is known that bakkōtō are forged through a secret technique of the Kasumiōji clan. Rukia noted that the Bakkōtō are highly illegal.