O-Ren Ishii was a member of the Deadly Viper Assassination Squad known by her code-name Cottonmouth. She was born on an American military base in Tokyo, Japan. She is a half Chinese-Japanese American who was the daughter of a military man and a housewife.
It is presumed that her very early childhood was untroubled as little is known about her infancy. Her father was a Sergeant Major in the United States Marine Corps.