Shichika Yasuri's older sister and a character from the Katanagatari franchise.
Nanami is introduced as a weak and fragile child with a blunt yet kind hearted personality. She received no official training in martial arts and her brother, Shichika Yasuri, was chosen as the next head of the Kyotouryuu swordsmanship style.
Nanami, along with her brother and her father, grew up isolated on Fushou Island. Originally, she was intended to be the next head of the Kyoutouryuu fighting style but her father felt that he was unworthy to properly train her due to her powers, which he deemed as deviant and unnatural. Despite this, Nanami still have obtained master level abilities in the form.
For Nanami, observing is training. She has the ability to learn any technique after seeing it once and master it after seeing it twice. During her fights against the Insect Squad of the Maniwa Corps she displayed this ability. Kamakiri Maniwa possessed the ability to grow claws from this fingernails and used this multiple times against Nanami, allowing her to master it. This ability played a critical part both offensively and defensively against her battles with the other members of the insect squad. Chouchou Maniwa had the ability to make himself and object that he carried weightless. After seeing this once, Nanami was able to use it to hang from a flower and position her self for an assassination move.
Nanami is somewhat fragile and ill, but her body is incredibly resilient and seemingly refuses to die when confronted with poison and disease. She displays this ability in her battle with poison expert Mitsubachi Maniwa when she is able to withstand two direct injections of his potions and feign illness long enough to retract the barbs (using the claws gained from her battle with Kamakiri), enhance them with another poison and use them to fatally infect Mitsubachi.
After defeating the Insect Squad, Nanami leaves her island to inform Shichika of a flaw in one of his techniques. In order to draw him to her, she seeks out one of Shikizaki Kiki's Twelve Deviant Blades and creates a path of death of destruction in her wake, which includes the complete destruction of a multiple villages, temple of monks, and hundreds of dead civilians. Eventually she acquires the Akutou Bita, a blade with regenerative abilities that removes her frailty, allowing her to better use many of the new abilities that she has acquired while on her murder spree.
Togame and Shichika eventually fight Nanami, although Shichika is reluctant to do so until Nanami attacks Togame. During their battle Nanami reveals that she wants to die at the hands of her brother and she fights him using her true powers and without Akutou Bita, which destroys her body.