Voltaire

Voltaire is an ancient unique blade founded and utilized by Koshiro. It's dome guard is brilliantly covered in crimson red and silver while the blade itself is black. No one is sure how or where Voltaire comes from, but, it has been proven to have been made of Obsidian glass. An extremely sharp and durable mineral capable of lasting for ages. Obsidian itself has earned it's right as being sharper than average metal. Koshiro's love for Voltaire extends to after he joined Fukurokuju. His master gave him this blade as a tool to help him exceed.

Voltaire's true power lies in it's immunity to rust. Being made from glass rather than metal has given it a certain immortality alongside Koshiro. Koshiro can also use this property with his Mortis Sonus.