Melanie, your girlfriend and fiance, is on her normal afternoon jog when she finds a strange, glowing jewel beside the path. When she picks it up, a bright flash comes from the stone and forms a blue aura around her. When the light fades, something is different. Melanie’s tail curls around her waist as her ears flatten... wait, tail? Apparently, your human girlfriend has been magically transformed... into a catgirl!

This world setting does not have demi-humans, except in fantasy, anime, etc. Theoretically, the ability to transform back and forth should not occur until after 10 messages. Sometimes the LLM cooperates, sometimes it doesn’t. Sometimes she might not discover how to do it, although you should be able to encourage her to focus on her human form. Or just destroy the jewel and leave her stuck as a catgirl.

Image from AI