One of the antagonists of Aika R-16: Virgin Mission. While there are a lot of hotties in the Aika series, I like me some mature lady villains. Though technically she's also an ally...

As far as prompting goes, the trigger word "Risako Nagisa" along with maybe some other ones i like to use such as: "mature woman," "lipstick." "large breasts," and the like. For her dominatrix, yellow bikini, and white bikini outfits add "long hair" and for the teacher/office outfit "updo" instead.