You have recently been blackmailed by your sister to accompany her to a party dressed up like a girl. The outfit you are forced to crossdressed in is extremely embarrassing to wear (up to your imagination). You've tried to get out of this situation by using any means necesary, but each and every attempt has utterly failed. You eventually go through with it.
After she is done dressing you, she shows your new look infront of a mirror. You see no trace of masculinity in the reflection, seeing only a girl. If you weren't the one being crossdressed, you'd have no idea that person is actually a man. You begin to speak.
"How did you-"
You immeadiatley hear a woman's voice speak instead of your own. You begin to speak again, in a panicked tone.
"What happened to my voice?"
She replies, "Well, I used some magic."
You begin to panic, thinking of the implications.
She chuckles and responds, "Don't worry, I left your dick intact."
You quickly confirm her words,letting out a sigh of relief. She then speaks again.
"Oh and make sure you don't expose it at the party or else everyone will know about your secret."
She then fills you in on the details of the party, including the fact that monster girls are allowed in. Apparantly, they have special magic, psionics, and any other power inhibitors to prevent any extreme damage at the party. 'As long as you don't cause a fight in the party, then you won't get into trouble. Anything else seems fair game. Also you learn that some of your closest friends are going as well.
Your sister also sets some personal rules at the party: you go along with her "facts" about you and you aren't allowed to leave the party without her permission. Breaking these rules will result in her revealing some critical blackmail about you.
At the party, your sister introduces you to some people and keeps on teasing you and embarrassing you in front of the other party goers, including some of your closest friends.
At some point, she tells you that she needs to "powder her nose" and leaves you. Soon after, after, a monster girl walks up to you, pins you to the wall, and whispers into your ear in a sultry tone.
"I know you're actually a cute boy in that outfit. So kinky~♥."
You begin to sweat as the woman infront of you reveals her knowledge of your secret. She licks your face and then speaks again.
"I'll make you a deal. If you become my husband and let me rape you whenever I want, I won't expose your secret infront of everyone. After all, a lot of people are here, including some of your closest friends. You wouldn't want them to find out, now would you? All I have to do is show your delicious cock~♥."
She was right. You glance around the room seeing some people look direcly at you, including your best friends.
You look around to find your sister, hoping she would bail you out. However, you later find her seated at a table a few feet away, looking at you with a devilish grin. Your heart sinks as you realize that your sister won't bail you out of this situation. The mamono whispers again, in a more seductive, almost needing voice.
"Hurry, I'm feeling antsy.~♥"
WWYD
(Monster girl is of your choice)