Star was in front of the Interdimensional Mirror and dancing. 

Star: (singing)  I just called 'cause have to say, happy birthday on your birthday day, happy birthday on your birthday day! (talking) And ... there's a special delivery coming right your way, your favorite.

She had a tray of cupcakes with small fireworks coming out of them. 

Pony Head: Ah, oh my goodness! Thank you so much B-fly! (realizing she was overreacting) I mean, a princess such as myself, could never tolerate such confections. But would you please donate them to the starving bartendens of Galafamor on my behalf?

The Crown Princess of the Butterfly Family was shocked. She never expected Pony Head, who she had been close to since childhood to talk like that. The rebellious Unicorn Head sounded much more refined and polite like that. 

Star: Did you just bump your uni-horn again? 

Pony Head: Girl, you know we can't receive packages here at St. Olga's School for Wayward Princesses. 

Star: AAAAAAAAAAAAAAAAAAAAAAAAAAGH! ST. O'S! ST. O'S! ST. O'S! 

Star threw the cupcakes to the ceiling and ran in fear. 

Pony Head: B-Fly? 

Star came out of a chest. 

Star: I can't even stand to hear the name of that place.

She shuddered in horror as her boots quivered a bit. 

Pony Head: Oh, please, you've got to be chill B-fly. I'm the one doing hard time here!

Star: I know, but if you weren't there we could totally party it up! Rainbow tea at the Dowager Room, sliding down the twisty slopes of Zala Mountain, then dancing all night long at the Bounce Lounge!

Pony Head: Oh hell yeah girl! That would be the best birthday day ever! BOOM! 

Suddenly the door opened and the staff of St O's grabbed her! 

Pony Head: OH NO! I EXPRESSED MY INDIVIDUALITY THAT PUBLICALLY SHOWED AN EMOTION! AND IT'S MY THIRD STRIKE! NO NO NO NO NO! THEY'rE GOING TO PUT ME IN SOLITARY CONFORMENT! 

The call was then cut off. 

Star: PONY HEAD! NOOOOOOOOOOOOOOOOOO! WAAAAAAAAAAAAAAAAAAAAAAAAH! YOU DON'T DESERVE THIS!!! 

Pinkie: Hey, did I hear someone had a birthday part?! 

Pinkie burst in with a big cake! 

Pinkie: Here Star, for your bestie! 

Star: WAAAAAAAAAAAAAAAAAAAAAAAAH! This is terrible!  Best friends don't let best besties have bad birthday days!

She blew her nose with a tissue. 

Star: And Pony Head is having the worst one ever. 

(Y/N): Hang on a minute. Wasn't Pony Head at St. Olga's School for Wayward Princesses? 

Star: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAGH! 

You shut her mouth. 

(Y/N): Star, it can't be that bad. Her Dad said it's just reform school. 

Star: NO! That's the calm way of putting it! It's a prison! A PRISON! 

Pinkie: PRISON?! YOUR BEST FRIEND IS IN THE BIG HOUSE?! THE STONY LONESOME?! THE ZOO FOR CRIMINALS?! THE OLD HOOBAH DOOBAH?! 

(Y/N): The Old Hoobah Doobah? That's not a saying Pinkie. 

Pinkie: It is too. 

Star: It's horrible! Nobody's ever escaped from there! 

(Y/N): Well, one of my best friends, Luffy, he told me he broke into a maximum security prison to try and save his brother. He made a lot of allies in there. And he managed to escape from that prison. 

Pinkie: And it was stated no one could escape from there before! 

(Y/N): So, let's go in and break your buddy out! 

Star hugged you guys! 

Star: I couldn't ask for better friends! 

Soon... 

You, Star, and the Rainbooms arrived at a rocky field. 

Rainbow: Okay, I think we made the wrong move. 

(Y/N): No, this should be the place. 

Star: I'm usually pretty accurate with these scissors. 

AJ: Hey, does anyone hear that? 

Twilight: What is it Applejack? 

AJ: Shh! Listen. 

Everyone stopped and listened and- 

(Y/N): CARRIAGE! 

You pulled everyone out of the way as a carriage rolled on by. 

(Y/N): That's our meal ticket. 

You all followed the carriage to see a massive castle. 

St. Olga's Reform School for Wayward Princesses (A correction facility to "reform" rebellious princesses!) 

Fluttershy: So ... that's St. Olga's Reform School for Wayward Princesses? 

Star nodded in fear. 

(Y/N): Yeah, this is creepy. 

The carriage had a bunch of princesses come out as a little man greeted them. 

Gemini (The Second in Command of St. Olga's! He is very strict and makes sure that the rules are enforced! Very loyal to his boss! Voiced by Jeff Bennet!) 

Gemini: Ah yes, the newbies have arrived. Welcome to St. Olga's School for Wayward Princesses.

Lightning struck as Star screamed. 

(Y/N): Hmm ... hang on a second. 

You used Transformation Magic to transform into a girl with big breasts. 

(Y/N): Okay, now that I blend in. We need disguises. 

Sunset: Could you always do that? 

(Y/N): After I joined Fairy Tail, yes. 

Rainbow: Pretty awesome, I have to say. 

(Y/N): Okay, now- CLOTHES BEAM! 

You gave each of the girls an outfit that made them look like princesses. 

Rarity: Wow, this dress matches my hair. Thank you (Y/N), Darling! 

(Y/N): Hey, we're going in style. 

Star looked like a rebellious princess. 

Twilight: Wait, what about you (Y/N)? 

(Y/N): Well- 

You had to change into a pink dress. 

(Y/N): Okay! Let's do this! 

Star: Hey (Y/N), you look cute as a girl. 

(Y/N): Thanks Star, I'll take that as a compliment. 

You all ran to join the new arrivals. 

Gemini: Yes yes. Single file. Ms. Heinous is eager to start the reformation process. 

Twilight: Ms. Heinous? 

Sunset: She must be the one in charge. 

Soon... 

You all were brought before the head of the school. 

Ms. Heinous (The Head of St. Olga's! She is a vile and cruel woman who believes in sucking out the individuality of princesses in order to keep them in line!) 

Ms. Heinous: Every one of you is here for a reason. 

She looked at all of the princesses. 

Ms. Heinous: Too wild. Too opinionated. 

One of the princesses blew a bubble from some bubblegum, and Ms. Heinous popped it. 

Ms. Heinous: Too bubbly. As part of a noble lineage, you don't have the luxury of being an individual. So by the time I'm done with you, you'll all be fixed. Every last one of you. Whether you're from Pixtopia, or Mewni. 

She went to Star and touched one of her heart cheeks, causing her to shiver in fear. 

Ms. Heinous: And don' even think about escaping. 

She took a pair of dimensional scissors from one of the princesses' hands. 

Ms. Heinous: These are useless. We have a Tramorfidian crystal in Tower 3. No rift can sustain itself within our walls, so you might as well cough up the scissors you smuggled in.

All the princess groan and drop their dimensional scissors. 

Star is about to drop hers, but you stop her. 

(Y/N): It's okay. We need them once we save Pony Head and disable that crystal tower. 

Ms. Heinous: That concludes your orientation. I'm confident that you will all become perfect princesses. One way, or another.

Gemini: Now to get everyone checked in so we can start sucking the individuality out of you. 

AJ: Grr! These people make me sick! 

(Y/N): You're right AJ. They can't just do this! 

Twilight: It's like they're stripping away what makes the princesses them, by force even! This isn't a reform school, it's a prison! 

Rainbow: Hey girls! I heard that the first one to check in gets her own room! 

(Y/N): Good thinking Rainbow! 

The princesses get all excited and run off. 

Gemini: RESPECT THE QUEUE! RESPECT THE QUEUE!

Gemini and his men began to chase after them while you sneak around. 

(Y/N): Okay, here's the plan. Star, Twilight, Sunset, and I will go and rescue Pony Head. That leaves, you five to go and disable the Tower. 

AJ, Rainbow, Rarity, Pinkie, and Fluttershy: We're on it, (Y/N)! 

(Y/N): Good. 

Twilight: Be careful. 

You all then split up, determined to save Pony Head and shut St. O's down!