Kei features in the 1999 animated short "Slave Sisters" as one of two orphaned sisters shackled by their parents' unpaid debts. Seeking both repayment and a secure future, the sisters submit to enslavement by a clandestine organization. Kei endures instruction from a male mentor who utilizes psychological manipulation and logical persuasion to craft her into a submissive slave. The training systematically conditions the sisters to serve the organization's objectives flawlessly, with the instructor committed to sculpting them into docile servants exclusively through non-physical control tactics.