Mutsue Yasuri (鑢 六枝, Yasuri Mutsue) was the sixth head of the Kyotō school of Japanese sword martial arts, the late father of Shichika Yasuri and Nanami Yasuri, and the person Togame initially sought for the mission to find the Deviant Blades.
Although he is a human, he thinks of himself as a sword, such as he thinks that there is no meaning to a sword that does not cut, due to his logic, as a sword, he does not need emotions or to think, or to feel anything.
Mutsue Yasuri is a tall, muscular man with wild aggressive appearance, which can oppose his personality.
After killing Takahito Hida, Mutsue and his family were exiled to an uninhabited island in the country of Tamba. He is later revealed to have attempted to restrain Nanami's power and denied her succession to the Kyotō art despite his willingness to, not because of her gender or frailty, but because he was simply unable to raise such an exceptionally powerful individual, also noting that she had the same eyes like those of his father. After training Shichika in the Kyotō art to become his successor, Mutsue requested Shichika to kill him, which Shichika fulfilled.
He is a master practitioner of Kyotōryū.
- Mutsue Yasuri literally translates to "Six Branch Rasp". His children's names represent flowers and fruit, products of a tree's branches.