Crossover A Certain Administrative Isekai (A Certain Mental Isekai / Sanctioned)

In which an eldritch entity accepts an inadvertent invitation to occupy a clone of Academy City's friendliest mind controller, Shokuhou Misaki. Meanwhile, Misaki is both dismayed and horrified to learn that she now has a new little sister to look after. Apparently, someone decided that the experiment responsible for replacing her memories with implanted, impossible imitations was worth replicating with as few biological differences as possible. As if she didn't have enough horrors on her plate already, right?