Bakuzan

Secret Sword Bakuzan is a special sword used by Satsuki Kiryūin with the ability to cut Life Fibers. It was split into Bakuzan Goko and Bakuzan Kōryo after Satsuki is defeated by Ragyō Kiryūin.

Secret Sword Bakuzan
Satsuki Kiryūin owns Secret Sword Bakuzan, and it appears as a black katana, and is very powerful, able to fight evenly with the Scissor Blade.

Bakuzan Gako
The Bakuzan Gako appears as a small dagger and is wielded by Nonon Jakuzure. She gives it back to Satsuki after rescuing her.

Bakuzan Kōryo
The Bakuzan Kōryo is larger than the Bakuzan Gako, appearing to be a short sword. It is wielded by Ira Gamagōri at first, but is given to Uzu Sanageyama as Gamagōri states that it is "more your thing". Sanageyama gives it to Satsuki after she was rescued.

Trivia

 * Satsuki's big toe's toenails are made of the same material as the Bakuzan.