His character ties-in to the, Below Freezing Point, Hellfire and Decisions, Decisions scenarios. Yoko is one of eight survivors that encounter perilous situations during the Outbreak in Raccoon City. However, once she gets hung up on something, she's a bit slow on the uptake with other things.

She has a quiet and reserved personality, but the strength of her inquisitive mind emerges with a toughness that surprises. She calls herself a University student and is very knowledgeable about computers. Greg Mueller operated on her to alter her memory, make her forget about the incident possibly to cover up the existence of the lab. In 1996, Yoko took part in an experiment, which was donating her cells as a base to develop t-Virus, without her knowing it, after a 'little incident', she found out the truth. At some point, Yoko joined Umbrella as an employee of Dr. William Birkin, working in his Laboratory eight miles underneath Raccoon City. Born in the United States, Yoko learned to speak Japanese through her mother.

Resident evil outbreak file 3