Star is having a conversation with both of her parents via an interdimensional mirror in her bedroom in the mansion. 

River: Of course, very few are aware of the serious matter, so I'll be traveling afar to give an all-day lecture explaining the proper throne posture. Slouched shoulders are an epidemic among nobility these days.  Blah-blah-blah, posture. Blah-blah-blah, back problems. 

Star was growing bored to the point where the pink heart marks on her cheeks turned into hourglasses. 

Star: (quietly) This is what it's like to be bored to death. 

Moon: Wait a minute, Star, are those dimensional scissors? 

Star noticed she had the scissors near her. 

Star: Uh ... n-no! Of course not Mom! These are ... normal scissors. See? 

She used them to cut some paper, only for a portal to open up and a monster to start coming out. 

Moon: Good. Because you're not supposed to leave Remnant until you're ready to become a Queen. 

Star: I know. I would never dream of leaving Remnant now! I love it here! I already made friends and everything! And I got a good teacher too! 

River: Glad to hear that. 

River then noticed his watch. 

River: Oh sorry, your mother and I must cut you short. You see I have a lecture to get to. 

Moon: You know him and his lectures. 

Star: Okay, bye Mom, bye Dad! 

She then shoved the monster into the poratl and closed it. 

Star: WHEW! 

(Y/N): Hey Star! 

Star: I WASN'T PLAYING WITH PORTALS! 

(Y/N): Well, I got a surprise for you! 

You had Team RWBY and the Rainbooms together. 

(Y/N): I promised some of my girls a trip to Mewni! 

Star: 

https://youtu.be/ZZLE1WnqYC0

Ruby: I got the fanny packs! 

Pinkie: I got the snacks! 

Star: Well ... I think ... maybe we should try something else. 

(Y/N): Oh come on Star, what's wrong? 

Yang: Yeah, don't flutter away over nothing. 

Pinkie: BOO! 

Star: Yeah, that was terrible Yang. 

Twilight: You seem nervous Star, what's wrong? 

Star: Me? N-NOTHING! I just ... well ... I- 

(Y/N): Star, what are you hiding? 

Star: I'm not hiding anything. I'm a-okay. Just got a bit of anxiety due to living here for quite a while. 

(Y/N): Well, there's no time to waste then! 

Later... 

You all came out of the portal and arrived in Mewni. 

Sunset: Well, this brings back memories of Equestria. 

Blake: Medieval society ... check. 

Weiss: Poverty ... check. 

(Y/N): Yeah, looks legit. 

Star: Welcome to Mewni! 

Ruby and Pinkie were taking pictures of the area. 

Ruby: Hey Star, is this where you grew up? 

Star: No-ho-ho. I live up there. 

She pointed to a large castle. 

AJ: Yep, fitting of royalty. 

Star: Higher. 

Next we see an even bigger castle in the clouds. 

Rarity: That is such a wonderful looking ca- 

Star: Higher! 

Then we see Butterfly Castle! 

Rarity: (amazed) OOOOOOH! 

Weiss: So are we getting the grand tour or- 

Star: Uh ... I think it's best if we look around and see the real Mewni experience. 

Fluttershy: Star ... are you okay? 

Star: Y-Yeah ... of course. Just got the feeling it would be best if we stay around here. 

The slums are full of things like a woman caring for 14 children, a herd of 12 pig-goat hybrids which Fluttershy was hugging and petting. 

There was also a little boy eating some food. 

Ruby: Hi there! 

He hissed and ran off! 

Ruby: Uh ... h-hi. 

Merchant: Get your Hydra tarail apples! 

Merchant 2: Half-off shrunken goblin heads! 

Merchant 3: Want pickled giant's toe? It's good. 

Rainbow: All sound like things you see in an RPG game. 

Yang: Eh, there are better deals at Wiz and Vanir's shop. And they were servants of the Demon King. 

One merchant was selling things like sundials, wind chimes, chickens, and jewelry. 

Rarity: THOSE JEWELS! THEY- 

The fashionista was so attached to the jewels that she grabbed them and paid upfront. 

Rarity: Look Applejack, this will be perfect for the new dress I'll make for you!

AJ: Always thinking about me, aren't you? 

Rarity: Anything for the apple of my eye. 

AJ: Hahahahaha. 

They both blushed and AJ kissed Rarity on the cheek. 

Star then noticed River nearby. The patriarch of the Butterfly Family was buying a spear. 

Star: D-DAD! 

River: Huh? 

Star quickly dragged you, Ruby, and Twilight to her. 

(Y/N), Ruby, and Twilight: AGH! 

(Y/N): Star, what ar you doing? 

Star: My Dad's here. 

Twilight: Your Father? The King is here?! 

Star: Yes! I don't know what he's doing here, but if he sees us, I'm dead! 

Ruby: Hey, I'm sure your Dad is understanding. He seems like a nice guy! If we explain to him- 

Star: Ruby! You don't get it! My parents told me I can't leave Remnant! 

(Y/N), Twilight, and Ruby: WHAT?! 

Star: SHHH! 

Twilight: Okay, we've done enough sightseeing, so let's go back to the mans- 

Star: NO! Everyone else is enjoying my gift! I don't want to ruin this for them! 

Rainbow: Hey guys! 

Sunset: Is everything alright over there? 

(Y/N): Uh yeah. 

Star: Next I want to show you all ... uh ... 

She saw a forest nearby. 

Star: Mewni's natural beauty! 

Weiss: Uh ... 

Weiss saw a sign nearby. 

Weiss: It says "Forest of Death." 

Star: Oh that's an exaggeration. 

Weiss: This doesn't have monsters or traps in here, right? 

Star: No. Look! A Carnivore Blossom! 

You all walked into the forest.