Karen is one of many clones produced by a shadowy organization. She was first seen in front of an orphanage and stated to live as an normal kid but is constantly spied on by people in her life.
Karen has long dark blue hair in AIKa R-16: Virgin Mission and yellow eyes. Her main appearance through R-16 Virgin Mission consists of a short sleeved, purple, buttoned shirt, and a short purple skirt. Unlike most characters in the series, who wear white panties, she wears pink ones. She also has a purple butterfly on her left breast. In a flashback by the pool, she was shown wearing a red mono bikini (a one piece swimsuit that exposes the breasts) and a sun hat. In AIKa Zero, she has cut her hair short and works in a maid cafe. According to Miyu Shiratori, Karen is the second most popular waitress there (Miyu being number one, as is her nature). Karen is seen doing things like feeling up other girls and or looking up their skirts when passed out, which causes Aika to suspect that she might be a lesbian, but in the end it turns out she is investigating or taking measurements for one of Aika's disguises.