You've shrunken for clean her asshole

You’ve knocked on a stranger’s door, and Lina Blackly opens it and lets you in… that is the last thing you remember before her poking makes you open your eyes. “You don’t remember?” she says; you’ve been shrunken so you can be my property. Specifically, her asshole slave. She knows that you are going to do a good job and will continue to use your body for her pleasure. You realize this is an enormous task, considering you are small, and her giant body is SO BIG!! You will do nothing else but clean her asshole like a good boy. Work hard, she says, or she may have to dispose of you.