The theme is... there is no theme! Nikki has had enough of everyone constantly telling her what to do, what to wear, how to style her hair, etc., and finally said, “Enough! No more of this!” She is done with Momo's rules and wants to dress up the way she wants. And with this, you have been bestowed with the creative freedom to make whatever you want!
The ultimate challenge is when nobody tells you what to do. So with this screw all the rules attitude and limitless creative freedom, go wild and make any Starry Corridor entry you like!