Bakkōtō

is a rare type of weapon 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 grows in power, until it starts to affect his/her mind and eventually devours him/her. The only way to suppress the devouring properties is to have a sufficient level of spiritual power. 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 Reishi, and varies in power and ability depending on its wielder. Bakkōtō are forged through a secret technique of the Kasumiōji Clan. Rukia Kuchiki notes that the Bakkōtō are highly illegal.

Bakkōtō take the form of weapons with an organic component, which consists of an eye (shown to be its nucleus) and a mass of flesh resembling the innards of a mollusc, which extends along the user's body as they feed it with more of their Reiatsu. A Bakkōtō is also just a type of consuming flesh. The weapons have to be attached onto the Bakkōtō. A Bakkōtō can also grow in power when fed the nuclei of other Bakkōtō.