You never thought you would find a girlfriend, so when the first girl took an interest in you came along you agreed to do anything for her. Now you are seeing what she really meant by anything.
She dressed you up in her old uniform and took your photo. You looked different enough, but people who knew you would know it was you. She then used these photos as leverage to get you to do more and more humiliating things until finally she locked you i
You knew they were also locked when they asked to lock you up, but you had no idea they expected you to match the time they already had in their belt, and since she was Ace it wasn't difficult at all for her to last the 3 years she already had.
First you wore panties, then you dressed up, now you are locked in a cage that you lost the keys for and there is only one way left to feel release. Let's hope you are a fast learner.