Swan dive (BNHA)

The attack

Izuku tried to slow his breathing as he looked down at the villains below. Aizawa still seemed to be glaring at him but eventually the hero nodded.

"Fine."

Izuku nodded back and got ready to attack. "The others are just cannon fodder. Nothing to worry about. Let's go!" Izuku yelled and disappeared through the floor, appearing only a second later behind Shigaraki.

He aimed for the villains head but Shigaraki moved, dodging to the side and turning to look at Izuku. "Looks like the Ghost brat came to play. Not going to run away like last time?"

Shigaraki tried to grab Izuku's head but his hand passed right through, giving Izuku the chance to rip the hand from the villains face, throwing it across the building.

Bakugou heard the sound of something flattering to the floor and saw it on the floor in front of him. He reached out to grab it, not processing the yelling from the rest of the building.

He didn't notice when a purple warp gate opened behind him, or when his classmates made their run for the exit. He grabbed the hand and turned it over, looking around to see where it had done from.

In the centre of the building, villains swarmed, being fought back by two people. Aizawa and another he strangely recognised.

They had white hair and a mask covering half their face. A pale blue cloak hid most of their body but he could see the glimmer of knives flying from their hands ever few seconds.

They flew around the USJ, taking down villains and battling a blue haired man, wearing hands the same as the one he know held. The hand must be the villains.

 "Bakugou!" Someone screamed. Bakugou turned to see purple mist rushing towards him. He kept back, using his quirk to stabilise himself and flying up at the villain. He kicked the villain and tired explosions at it as fast and he could, forcing it back towards the doors.

 He attacked again and pinned Kurogiri down. He smirked at the pinned down villain, holding him down by the metal plating on his neck.

 "Try anything and I'll blow your ass up so bad they'll be piecing you back together for weeks."

 "That doesn't sound very her..." Kirishima's voice cut off and Bakugou turned to look for him but instead saw an empty space. Suddenly, a villain landed there, an axe digging into the ground where Kirishima has been standing.

 "Aaaaaaaaaaaaaaaaaah!" Kirishima seemed to fall from the sky and landed on the villain, seeming just as surprised as Bakugou.

 "Sorry! Never actually tried picked someone up before." The person who was fighting before floated down, stomping on the villains head as they talked. "I'm Phantom, a vigilante. Now, the blue haired boy made it out, right?"

 Bakugou nodded nervously. The vigilante looked at him and seemed to smile, but he couldn't help but notice how their hands were shaking as they nodded at him and ran back to where Erasure head was fighting.

Izuku started to fight alongside Aizawa, trying to explain to him was they went. "The- students are... Still in the US, J. Kurogiri - teleported. Them around. They should be able to take the... Villains, One made it. Out. He should be able to, get, more, heroes."

Shigaraki's hand passed through Izuku's head but he just smiled at Aizawa and kicked at the villain, pushing him backwards.

***

Through the windows that made up the ceiling of the USJ, Rei watched the fight, nervously twirling a knife in her hand.

Izuku was fine on his own, right? He wasn't struggling. He could fight the villains alone. Anne she shouldn't go anyway. Toru might recognise her. If she did, then her parents would find out and... 

She didn't want to think about what would happen.

She flew around the windows, looking to see if she could find Toru. If course, trying to find someone who's invisible isn't that easy and Rei couldn't spot her. She just made her way back to where she could see Izuku and watched him fight.

She turned and looked in the dirsction, hoping to see heroes approaching. Luckily, she saw the familiar form of All Might, rushing through the trees, though he was still a few minutes away. At least he would be there soon. It would be okay.

Izuku would be okay.

Through the glass, she heard a strangled scream and turned to see Aizawa, pinned under the Nomu. Izuku ran to help him, punching at the villain, but it grabbed his hand while it was solidified and the him across the USJ.

Izuku stopped by the doors and grabbed his head, fighting the dizziness and nausea as he flew at the Nomu again, reaching to save the hero trapped beneath the wall of muscle.

Rei used her quirk to rip the window apart and rushed to Izuku's side, saving him from being thrown back again.

 "It's okay." She whispered. "All Might's coming. He'll be here soon."

 Izuku looked up at her. "R- Spectre! What if she sees you?"

 Rei winced then glanced around, not seeing any floating clothes that might indicate that her sister was there. "It's fine. It's not like she'll recognise me. Besides, he could recognise you." She nodded her head towards the doors, where Bakugou stood with Kirishima, fighting off some villains.

 Izuku slowly nodded and turned to the Nomu. Rei turned as well and nodded to Aizawa. "Can't die now, you still need to say sorry for catching me that one time. Also, Mic nearly deafened me, so he owes me too."

Aizawa recognised the vilante's voice and wanted to say something, but he couldn't move, he couldn't even look up at them. Instead, he just have an annoyed groan.

Rei laughed. "Ok, then. My favourite foods are pancakes and ice cream." Aizawa groaned again. And Rei laughed.

"Nomu!" Shigaraki yelled from behind them. The Nomu seemed to react immediately and lunch at Rei and Izuku, still pinning Aizawa down. It's fist left a crater in the floor where the two had been standing. Rei glanced over at it.

"I know I said I like pancakes, but I don't wanna be one."

Nomu got ready to punch again and the two vigilantes stepped back, more out of instinct than anything. The Nomu seemed to choose who to aim for and brought its fist down.

The floor splattered with blood.

***

One thing I would like to clarify with Izuku's quirk:

He cannot chose what passes through him, and that what doesn't. He can make parts of his body solid for short lengths of time, and during this time, nothing can pass through those parts of his body. This is why he can still get hurt, if the solid areas are targeted.