Katanagatari novel volume 4 was written by Nisioisin.

Swordless “swordsman” Shichika and self-described “schemer” Togame are on a quest to obtain twelve peculiar masterpiece blades. Unveiling the truth about the legendary katanas and their creator as part of a gorgeous tapestry of fates that vie to upend history itself, this paperback edition, featuring beautiful interior art and copious bilingual footnotes, is the last of a quartet collecting a best-selling series from the former homeland of samurais and ninjas.