Zankuro is a huge warrior who
traveled Japan relentlessly
During a time, he traveled
from village to village slaughtering people with no regard or disambiguation. Because of this, people started calling him a demon. One
night, while he was slaughtering an entire village, he is unable to kill
one child. Upon setting his eyes on the young girl, he can't bring himself to
kill her, and realizes the error of his ways. From this night on, he
retires his massacring and becomes a hermit, only drawing his blade to kill
worthy opponents in duels.
It is revealed that the child was Zankuro's daughter, Shiori. Zankuro had forgotten
about her due to his killing intent. Shiori eventually runs into
Haohmaru and asks him
to kill the "demon". Eventually,
Zankuro was challenged by Shizumaru,
a boy who also had a demon inside of him.
Zankuro was killed by Shizumaru and Haohmaru, and his body was buried and sealed by Gaira.
However, he was quickly revived by Amakusa
who wanted to use his powers. He was eventually killed again by Sogetsu.
It seems he somehow came back to life again since he appears in Genjuro's
ending in SS64.
In Samurai Shodown VI, his ending has Shizumaru bring Shiori to him with
Haohmaru encouraging the estranged family to reconcile. Feeling himself beyond
redemption, he refuses until Shizumaru convinces him not to submit to his inner
demon. Realizing the value of life, Zankuro decides to live on for his daughter.
He abandons the way of the sword and the two embark on a journey where he hopes
to repent for his sins.