Author POV
Luffy stands in front of a defeated Kaido, both bloodied and exhausted, but the winner is clear. Monkey D. Luffy has done it. He has defeated one of the strongest people in the world.
He can still hear the sounds of fighting still going on. He starts to walk back down to find his friends as he lurches, holding his own injured body up.
Luffy: I need to go help my friends.
???: Sorry, that's not going to happen kid.
Luffy looks back as he sees a man in a CP9 uniform. Luffy's Haki can tell he has malicious intentions, so he attacks.
Luffy: Gomu Gomu pistol!
His fist stretches out, but the man deflects his attack, which in turn forces Luffy to stumble and fall onto the ground, clearly exhausted from his previous battle, groaning and yelling.
Luffy: I don't have time for this! My friends need me! Gear 2nd!
Luffy gets up wobbly, slamming his fist onto the floor and activates gear 2 and goes on the attack.
Luffy: Gomu Gomu no Jet Pistol!
His punch lands perfectly on the Cp9 member's stomach. The man yells in pain but smirks as he touches Luffy's stretched out arm.
Member: Goodbye Monkey D Luffy.
Luffy's eyes widen as he sees a blue light around his arm coming toward his body and he finally blacks out.
Location Remnant: Forever Fall (Forest)
Luffy gasps and opens his eyes. He sees beautiful red trees around him. He tries to get up a little but lays back down from the pain but he doesn't question it.
Luffy: Shit I need to find my crew!
He looks at his body and sees how bloody he is which he groans.
Luffy: I need to get up!
He forces his body up as he limps, looking around for a while until he spots a black creature with a white skull and large claws.
Luffy: Oi!!! Can you tell me where I am!?
The creature looks at him and gives a loud roar as it glares at Luffy, ready to dash at him. Luffy looks back at the creature and glares back, sending a shockwave of Conqueror's Haki. The creature backs away in fear, despite its lack of spiritual energy. It knows that Luffy is dangerous, so it runs away.
Luffy: Oi! Get back here!
Luffy tries to run after him, but his injured body does not let him, forcing him to sit down.
Luffy: Stupid injuries.
He hears a noise coming from behind a bush until he sees a man with gray hair and a coffee cup looking at him. That man, being Ozpin, stares at Luffy with a look of curiosity, seeing him using the conqueror's haki.
Ozpin: Who are you?
Luffy: I'm Monkey D Luffy! I'm the man that's going to become king of the pirates!
Ozpin: King of the pirates?
Luffy: Where am I old man?
Ozpin ignores Luffy's rudeness but he answers him.
Ozpin: You are in Forever Fall. I came here after I sensed a force coming from here.
Luffy: Fover foul?
Ozpin: Forever fall.
Luffy: I've never seen this place in Wano it looks nice.
Ozpin: Wano? Monkey if you don't mind. Let me take you to make school to heal you up for now.
Luffy: My name isn't Monkey it's Luffy. And sure I've never been to a School.
Ozpin apologizes for his rudeness but also looks puzzled at him about him never going to school but decides not to question it. He helps Luffy up, but they both hear and see the creature from before staring at them along with more friends.
Ozpin: (Let's see how this boy scared that Grimm away last time.)
Ozpin doesn't do anything as he waits to see that same power that Luffy used to scare the Grimm away. Luffy opens his eyes and gives a deadly glare at them, not using his conqueror's Haki but one of annoyance. The glare is enough to make them whimper and run away quickly.
Ozpin: (How disappointing he didn't use that power he used a while ago. But that doesn't matter he has to get his injuries treated.)
Time Skip with Ozpin carrying Luffy on his back who is asleep
Luffy wakes up and looks around seeing a complete white room with machines and other stuff but he stares at his body and sees it covered in Band aids
Ozpin: I see you're awake.
Luffy: Old man where are we?
Ozpin: Keep still we have to talk.
As Ozpin explains to him, about being in another world, he was able to piece out that Luffy was from another world/universe due to the types of injuries he had, as well as him not having any record forms of him being alive on Remnant and that mysterious power he showed. He also tells him what type of planet Remnant is. He explains the Grimms, Faunas, and everything else he needs to know, although Luffy, being an idiot, really has no clue what he is talking about.
Luffy: I don't really get it but ok. What's your name old man?
Ozpin deadpans but answers his question.
Ozpin: I am the director of this school my name is Ozpin although I cannot do much to help, I will do my best to help you find a way back to your world. But can you tell me what that force was when you scared that Grimm away?
Luffy: I just used Conqueror's Haki.
Ozpin: Conqueror's Haki?
Luffy: Hai, anyone with a lower will, will fall onto their knees or go unconscious but it will not kill them... I think.
His stomach starts to growl as he feels weak from hunger.
Luffy: So hungry.
Ozpin: I shall take you to the cafeteria to eat, but first how old are you Luffy If you don't mind me asking?
Luffy: 18.
{I know he's 19 in the manga but it's for him to be more accepted as a first year.}
Ozpin: I will enroll you into beacon, students are forced to take a test first, but I already saw your potential in the forest. Can you walk?
Luffy jumps off the bed with a wide smile while Ozpin looks at him with wide eyes, seeing how easily he's recovered. He can easily tell that he is still injured, but his body seems to be healing at an alarmingly fast rate. The reason... Luffy's body works faster than a normal human, so by putting medication into his body it would naturally heal the injury quickly.
Ozpin: (Incredible he healed so quickly!)
Luffy: I feel much better thanks old man!
Ozpin: I-I see.
Ozpin leads Luffy through Beacons' hallways, where Luffy runs around looking at everything in amazement. They reach the cafeteria, and Luffy sees a lot of people eating and talking.
Luffy: Woah it's like a banquet here!
He walks toward the front as he sees all the food as he grabs a plate and starts to put food on it. Ozpin smiles, but as time passes, Luffy continuously puts food on his plate, to which Ozpin's face turns into one of horror.
RWBY and JNPR POV
Ruby: Hey it's not my fault that I didn't do my homework last night!
Weiss: Yes, it is! You were playing video games all night long!
They both keep on arguing as the other just look at them blankly
Yang: They sure woke up with a Yang.
Blake: Please Yang it's too early for this.
They reach the cafeteria, and they notice that it's quiet. They look at what everyone is staring at and they see a guy with a straw hat, some blue shorts, and a lot of band-aids, but the biggest eye-catcher is how fast the guy is eating his mountain of food.
Pyrrha: Is that evenly humanly possible?
Ozpin: It wasn't until I met this boy.
Both teams look at Ozpin, who is nervously counting how much money has been used to feed this one child.
Luffy: Ahhh that was good.
His stomach is extremely big, but he gets up as his stomach starts to go back to normal.
Luffy: Ozzy who are they?
Ozpin stops counting as he looks at both teams. And tells them to introduce themselves.
Jaune: I'm Jaune Arc, leader of team JNPR.
Pyrrha: I'm Pyrrha Nikos.
Ren: Lie Ren, just call me Ren.
Nora: I'm Nora Valkryie!
Ruby: I'm Ruby Rose! Leader of Team RWBY.
Yang: I'm Yang Xiao Long, the older sister of this little goof ball.
She rubs Ruby's head which Ruby grows embarrassed.
Blake: Blake.
Weiss: I'm Weiss Schnee, heiress of the Schnee Dust Company.
Luffy: John, Piera, Rain, Noah, Rody, Yam, Bleak and Waste. Ok got it!
Both Teams: That was very wrong!
They keep on arguing with him forcing him to memorize their names while Ozpin looks at them.
Ozpin: (Just what are you Luffy?)