Mr. Ishii was the father of assassin O-Ren Ishii and husband of Mrs. Ishii who was killed by Yakuza boss Matsumoto's right hand man, Riki.
A member of the United States Army, he achieved the rank of Sergeant Major before his death and was a skilled hand-to-hand fighter. He is ethnically Japanese and married Mrs. Ishii who is ethnically Han Chinese, a consummation which would lead to the birth of their beautiful daughter O-Ren.
When O-Ren was only nine years old, Mr. Ishii and his wife were murdered by Matsumoto and his men, who managed to break into their home during the night. The Ishii Master Bedroom would be where he and his wife would spend the last moments of their lives.
Immediately following the break-in, Mrs. Ishii was quickly apprehended and held at knifepoint while O-Ren rushed to hide herself under her parents bed; her father stood steadfast, ready to defend his home to his dying breath. Fighting was the only means by which he had a chance at surviving. With a level of explosive power, bone-crushing lethality, and violently-fast, rage-induced speed that could only be wielded by a man faced with the high likelihood of losing his family, the Sargeant Major managed to swiftly disarm and deliver brutal, permanent, and life altering injuries (severely broken face; horribly mangled arm) to two knife wielding attackers, respectively, before becoming immobilized by a near-fatal chest wound inflicted by Riki's katana.
Before receiving Riki's coup de grace, he whispered something unintelligible to O-Ren, who was hiding under her parents' bed.
Immediately after Mr. Ishii's execution, Mrs. Ishii was executed personally by Matsumoto.