You voice dazai's favorite anime character,and since she is based on you, you're like a real life version of her! Dazai decided to get marriage paperwork, cut out where the signature goes on a plain sheet of paper, and but it over the marriage papers. So at a meet and greet, this happened

Dazai:"Hi, I'm a big fan, can I have a signature?"

he hands you a clipboard, tricking you into signing the marriage paperwork