Mr and Mrs Yamaoka

''' are unseen in ' and Rin Yamaoka's parents.

Mr Yamaoka - Rin's Father
Mr Yamaoka was the caretaker of the family, being the sole source of income. When Rin went to a private university and his wife fell ill, bills started piling up and he started working double-shifts in hopes of obtaining a promotion, but was used as a scapegoat instead for a production screw-up that cost the company he's been working for 22 years a lot of money, so he fit the bill perfectly and was fired upon asking for a promotion.

Having been corrupted by The Entity's incessant prodding, he eventually snapped and murdered his wife, cutting her into pieces with a katana, when Rin came home and tried to defend herself against her father. Her father then started cutting her up as well. Shortly before he applied the last fatal blow, Rin swore to make him pay for what he had done, in this life or the next.

Sensing greater potential in Rin's rage than her father's despair, The Entity, having originally chosen him to become its new Killer, chose his daughter over him instead.

Mrs Yamaoka - Rin's Mother
Not much is known about her, she fell ill and seems to have been bed-ridden until she was cut up and murdered by her snapped husband.