“But don’t you think that sounds a little fishy? The more I hear, the weirder this all sounds. This guy may be old-fashioned and direct – but look what happened last time. Remember when he scrapped his loyalty to the bakufu and ran off with the sword?”
Hakuhei Sabi. The swordsman Togame hired before Shichika, expecting him to carry out her Sword Hunt. He was the strongest swordsman in Japan – although after his betrayal, he had earned himself the name of Fallen Swordsman.
But all the same – Sabi was a master.
“His level of mastery makes the venom of the Shikizaki blades all the more potent – and pervasive. Venom courses through his veins.”
“Wow.”
“Even before he came into possession of the Whisper, Sabi was such an exemplary swordsman he had ceased to come across as human – so perhaps this was inevitable. It certainly makes sense.”

Katanagatari Omnibus 2, Page 7