All Might repeatedly punches the Nomu in a clear attempt to defeat it. Well, while watching from the distance, something went wrong. The moment All Might smashes the literal bird-brain through the roof, a giant beam of light comes down from the hole and aims for Izuku Midoriya. Too bad, he was forming a harem before all this.

"AHHHHHHH!" He screams as he feels himself dissipating, the girls in his mini-harem screaming. All Might watches in horror as the ninth holder of One for All is dying in front of him. In an attempt to save him, All Might tries to dash into the light. Key word, tried.
He found himself not being able to get close to it, an invisible barrier blocking him from entering. The light fades, leaving nothing behind.
Oh well, time to switch realties.

Izuku's POV
'Jeez, where am I?' I say as I look around, seeing myself in the sky on a carpet. Reminds me of something I saw on a TV show..

In front of me is a old man, facepalming. "I did it again, didn't I." I hear the man say. He gets his palm off his face and looks at me. "Ummm, excuse me but where am I?" I ask confused. "I uh.. accidentally killed you." The man says, in an embarrassed tone. "K-killed me?! S-so are you Horokoshi?!" I ask, surprised. "No you idiot! I'm God!" He shouts. "Hm? I thought Horokoshi was God."

I say, thinking a bit. He sighs and continues. "Well, I'll give you the rundown kid. You have 2 options." He says to me, then takes a sip of his drink. "Either die permanently, which I know is unlikely for you to choose, or reincarnate but be in another world." He says bluntly. "Um.. will I still have my power?" I ask worriedly. "Oh, yes you will. This one is similar to yours actually, just.. how do a put this? In this world, men are treated as breeding machines, at a young age males are forced to learn how to make things at factories, do 9-5 jobs, etc. Women, are the dominant species. They have the power. But this world is a bit different, unlike the other one I accidentally killed, this one has all the people you know."

"Wait really?? Their alternate selves?" I ask excitedly. "Wait, there's a twist. Everyone you knew back then, is a girl. Women make up 93% of the population, so be careful out there because trust me, back then those feminists were wild." He says while chuckling a bit. "Feminists used to exist in this one? Not like they made a difference.."

"Anyway, what's your choice?" "Since males are the inferior species, I want to rise up and be the first male hero in this one!" "Now that's the spirit. Now, close your eyes for me." I did as he said.
All of a sudden, I feel a massive boost in energy as I feel my body changing. I look down to see my shirt ripped, but my shirt not being the only thing. I see those new muscles shrinking and my chest goes back to looking the same. "I just gave you a boost in your body and hid it. I don't want you to worry about sizes!" He says excitedly. I sigh as I again feel a massive boost, in power this time. "Okay, also gave you a boost in power.

This should help you survive in your next world, good luck!" "W-wa-" I get interrupted by waking up under a tree. "Whoa.. was that a dream?" I ask myself while standing up. Once I'm up, I see the UA building right in front of me. I sigh and just walk in. 'Thanks god, now I gotta deal with this."

I walk into the building and the alarms don't go off. Probably because I somehow have my UA card on me.
I can only guess class is going on right now, so I walk into the hallway with every other class. I hear a bunch of commotion coming from 1-B, and I chuckle. "Wait.. if I enter the class as a boy.. I'm screwed." I sigh as I think of something. I get a call on my phone from god and rush to the other side of the hallway. "Act like a girl!" God says, laughing a lot. I sigh as a skirt from the UA uniform and a wig appears in front of me. I grab the clothes while rolling my eyes and go to the nearest bathroom.
Once I leave, I look like a female version of me. Thanks to the wig that matches my hair color and hair type somehow. Well, for some reason I didn't think I had to do anything else. So I just slid open the door,

Bad
Idea.

3rd Person POV
"So, the Sports Festival will be starting soon and it will be a great chance to gain attention fr-" Aizawa gets cut off by someone sliding the door open. "DEKU?! WHY THE HELL ARE THERE 2 OF YOU?" Katsumi Bakugo screeches. "I-I don't k-know Kacchan!" The female version of Izuku, Izumi Midoriya. "Shit." Is all Izuku says as he runs out the classroom, swiping off the the skirt and wig God gave him.

He runs towards the principals office as he hears his phone ring again. "I'll uh.. erase their memories." God says, nervously. Izuku sighs of relief and knocks on the principal's office door. He hear a soft feminine voice come from the other side. "Come in!" The female Nezu counter-part says happily. Izuku opens the door and sees something he didn't expect to, Nezu, but as a short girl with white hair going down to her shoulders and blue eyes. Adorable, yet illegal in the worst way.

(this is how Nezumi looks like)
Izuku's POV
Her eyes widen as she sees something she's never seen but heard of. A boy, but she's still unsure.
"Whoa whoa whoa, what are you doing here? Are you a girl who looks like a boy or actually a boy?!" She says, scared. "I'm a boy. I uh.. wanted to come see you?" I say nervously. "Look, b-boys don't have quirks and I don't know how you got in the building but please leave.." She says nervously. "I have a quirk." I say bluntly. "Hm? S-surely you're joking.." "Nah, I can show you."

I normally activate One for All one of my limbs, but for some reason one of the boosts God gave me was also intelligence. I activate it throughout my body and a massive gust of wind surrounds the room. Her eyes completely widened as she sees me with green lightning appearing and disappearing in different places every instant. "Y-you.. have a quirk.." She says, relieved for some reason. I deactivate One for All and the lightning fades. "Sooo, can I join?" I say excitedly. "I.. have to c-check." She says. "Check what?" I reply nervously. "Just close your eyes and don't say a word."

I do exactly as she says, and I feel a hand feeling on my, well uh.. area. My face instantly goes full on red and I tense up. She grabs what seems to be my member, and starts to feel it in the best places. I back away quickly and sit down. "Y-Yep, you're a b- boy!" She says nervously, a shade of red forming on her cheeks. She takes a deep breath and continues. "Ok, I don't think you have to do the entrance exam so go on to class!" She continues. "Wait, what are they gonna think?!" I ask worriedly. "Not sure, but go ahead to 1-A! Here, take this with ya!" She answers, giving me a from saying 'Transfer.' "But also, make sure to visit tomorrow, right after school ends." She whispers in my ears, seductively.
I sigh as I walk out the door with the principal waving. I facepalm and walk towards 1-A.
'I'm screwedddd.'
I slide open the door, only for everyone in the classroom to stop talking. "H-hi.. everybody.." I say nervously. "WHATTTTTT?!" The whole class shouts, Aizawa having a shocked expression. "WHY IS THERE A BOY HERE?!" The female explosion shouts. "W-why does he l-look exactly like me?!" My female counterpart says confused. 'Why is he so cute?!' Katsumi Bakugo asks herself, confused. "Look, I don't who you are, but leave immediately or get arrested for being on private property." The female Aizawa says. "No wait! Look!" I say, scared of getting locked up.

She swipes the clipboard saying 'Transfer' away from me and takes a good look at me. "Are you a girl that has a masculine physic?" She asks, confused. "N-no, I'm a guy." I reply. "Yeah right, tell me how'd you get this and leave." She says coldly, her eyes now turning red. I swallow a massive lump in my throat and sigh. 'I can't speak.. I'm too nervous.. fine, I'll just show you.'

A red outline starts to form on me, and I hear a quick gasp from my alternate self. I shrug it off for now and spread it through my body.
Green lightning starts to form around me, giant sparks of green appearing and disappearing.

"S-s-see? I have a-a quirk.." I say nervously. 'Holy shit, why does it feel so much better to move in this form??'

Aizawa's eyes widening, her quirk already turnt off. "W-who sent you here?" She says, losing her strict composure. "Nezu."

"Who's Nezu?" Aizawa asks. "Are you talking about Nezumi? She sent you here?" She continues. "Y-yeah.." I reply. I turn off my quirk and bow down to the class. "I am Izuku Midoriya, i-it's nice t-to meet you all." I say nervously. "Midoriya? So you two are twins~" said by Mina Ashido. My eyes shoot to where she is, and she has one hell of a body. 'Oh shit it's about to be clonecest if I say that!' I think to myself.

Aizawa gives me the signal to sit down, right behind my twin. 'Where's Mineta?'

I sit down, finally noticing that I had a uniform on. 'It didn't appear when I first changed.. thanks god..' I say to myself, sighing.
I decide to make conversation, but I catch the eye of quite of few girls. I look around at them, all batting their head away and to their desks. I tap my twin on the back and she shudders as she slowly turns around.

"Y-y-yeah?" She asks, very nervous. "Can I speak with you after class?" I reply. "Y-yeah."

'I gotta act like I'm her twin. Plus UA is probably gonna keep me hidden, so publicity shouldn't be a problem yet. I'm gonna tell her my idea so it doesn't seem strange as to why I'm identical to her.