Kasumi A was born after the original Kasumi won the first Dead or Alive tournament. When Kasumi was victorious, DOATEC (Dead or Alive Tournament Executive Committee) abducted her. She was subjected to a cloning project which was intended to create a human weapon. Kasumi's DNA was copied and it was used to create a clone named Kasumi A. The clone was an exact match of the original Kasumi.
Before the second tournament, DOATEC instructed Kasumi A to sneak into the Mugen Tenshu Village. Her assignment was to capture Kasumi's brother, Hayate, who was in a coma from a previous fight. She managed to find Hayate but was caught by Ayane. They fought each other without any hesitation. Ayane was defeated and Kasumi A left with Hayate's body.
Ryu Hayabusa rescued Kasumi from the science lab. During Kasumi's rescue, she encountered her clone for the very first time. Kasumi A claimed that they were sisters and Hayate was hers because she would take care of him. Angered, Kasumi defeated Kasumi A in combat. The clone escaped the burning building. The original Kasumi and Ryu also escaped.
After the third tournament, Victor Donovan modified the genes of Kasumi A. She was transformed into a more powerful being entitled Alpha-152. He transported her to the DOATEC headquarters during the fourth tournament. The place was attacked by the Mugen Tenshin Ninja Clan at the same time. The clone somehow escaped in the midst of the chaos.
Donovan hid Alpha in a secret laboratory on an oil rig. Kasumi, Ayane, Hayate, and Hayabusa were invited to the rig by Helena Douglas who was the new president of DOATEC. She discovered Donovan created clones of Alpha. The clones were part of phase 4 which was their distribution to every major military. The shinobi searched for the lab where the clones of Alpha were held. They found it deep within the oil rig.
The original Alpha was awakened when the shinobi entered the lab. It fought Ayane and Hayate. At the same time, Hayabusa used his own energy to destroy the lab. Alpha engaged in a final fight with Kasumi. The clone lost and died. The shinobi then escaped the lab. Helena was able to cancel Phase 4 after the destruction of the lab, Alpha, and it's clones.
Kasumi A possesses the opposite personality of her counterpart. She isn't compassionate or friendly unlike the original Kasumi. Instead, she may display a malicious grin or amusing laugh whenever she is about to harm someone. Kasumi A can also be childish by acting like a kid who has too much power. The only people who she respects are Donovan and Hayate. She views Donovan as her father and Hayate as her own brother.