Kaya is the daughter of Shinichi Saimori and Kanoko Saimori and the younger half-sister of Miyo Saimori who is currently engaged to Kouji Tatsuishi. Kaya is very spoiled, entitled, and emotionally and mentally abusive towards her half-sister. She is also rather two-faced. Despite her polite public appearance, she is rather disrespectful and nasty in her actions when she believes she can get away with it, not only to Miyo but also to her boyfriend Kouji.