Kasumi was initially envisioned as a male character and was not going to be the protagonist. However, after changing the character's sex to female, series creator Tomonobu Itagaki became attached to her new design and decided to make her the heroine. Itagaki would go on to describe Kasumi as his “daughter”, and that she is “like a Venus” to him, as well as defending her sexualization among the rest of the series cast despite her canonical age of 17 years old being considered underage in countries with higher ages of consent like the United States. The now-defunct game journalism website QuickJump quoted him in 2007 as saying “in Japan, [the sexualization of a 17-year old] is okay. Maybe it’s 20 in America.”