Sissy Princess - Cinderella (Patreon)

I had this silly idea that instead of wearing shoes made of crystal, Cinderella has a chastity cage made of crystal.

When she gets to meet with the prince, the guy asks to see her "thing" without the cage. After taking it out, the time for her transformation is running out, so she escapes leaving only the cage behind.

Imagine the prince trying the cage on everyone in the town to see who fits in it. haha