"It was all my fault."

Those were the only words tumbling from Kayano's mouth that Nagisa registered as she stepped forward, her hair free from its pigtails and cascading down her back.

He didn't quite catch the rest, the bluenette was too high strung to be listening to monologues. His head hurt, like someone had thought it was a good idea to bang a hammer against it, and his vision was blurry. Everything was moving too fast and too slow at the same time.

Nagisa kept his eyes trained on Kayano's brightly colored hair. It stood out against the gloom, acting as a beacon to shine through the darkness of his headache. He vaguely watched as Kayano ascended into the sky, a knife clasped tightly in her hand and a determined look on her face as she evaded tentacle after tentacle.

The part of Nagisa's brain that was still alert raised an alarm in his head that wasn't helping his headache. There was no way this could end well. No matter how much assassin training she had had the past year, Kayano was still a 4'9" human girl up against a monster that could move at Mach 40. Yeah, the odds were definitely not in her favor.

Nagisa opened his mouth to voice this sudden realization when the inevitable happened.

Time stopped. Everything moved in slow motion. Nagisa's headache suddenly cleared while his jaw dropped, and his eyes widened.

Kayano…

Blood splattered to the ground like a crimson rainfall as Kayano's entire body went as limp as a rag doll's and allowed gravity to take over.

The tentacle that was the cause of this sudden change removed itself from her body as she fell, allowing for the blood to flow out of Kayano's body at an alarming rate.

A thud echoed throughout the clearing as Kayano reached the ground, unaware of everyone's undivided focus on her.

And then time started moving again, and Nagisa's headache was back in full force as he let out a breath he didn't know he had been holding.

But it was anything but a sigh of relief.

Memories flooded Nagisa's vision, and he allowed himself to get lost for a brief moment in the times he spent with Kayano. When she was smiling. And happy. Even though Kayano had intended for the year to consist of fake friends and memories, that was the opposite from the truth, and Nagisa had enjoyed being around her chipper and bubbly personality.

In the background, Nagisa faintly registered the horrid sound of Yanagisawa laughing, but he tuned it out. He needed to keep his bloodlust in check, so he didn't snap again like back on the island with Takaoka.

A breath, and Nagisa was pulled fully back into reality. His eyes darted to Kayano who was now gasping for air like it could be taken away from her at any second. Hope filled his chest and made him feel whole; Nagisa hadn't realized how hollow he had felt on the inside.

And the hollow feeling was back within a split second when he saw another tentacle lunge towards a helpless Kayano with the intent of actually finishing her off this time.

Without a second thought, Nagisa felt his body leaping into action. His peripheral vision caught the confused looks of the other 3-E members, but he pushed them out of his mind. He had to focus on saving Kayano. Koro-sensei was too battered to even think about moving at a normal pace, and no matter how much he wanted to, the octopus-like teacher would be unable to reach Kayano fast enough.

The bluenette sprinted like his life was on the line, and it was, only he was putting it more in danger by proceeding. Using the momentum of the full-on sprint, Nagisa ducked into a roll as he reached Kayano and threw his body over her, praying to any god that might be out there that he had made it in time.

Which was a silly thought because he would have hopefully noticed if a giant tentacle impaled Kayano for the second time.

Nagisa closed his eyes shut and braced himself for the impact, ignoring the shouts of his classmates as they realized what he was doing.

If he had been as alert as he normally was, Nagisa would have noticed the pair of eyes that had been trained on him from even before Kayano had stepped forward.

Then everything went black.

That's a lie; everything went white, and it sounded like someone was ringing a bell right in Nagisa's ear.

He couldn't feel anything, not even his body. And the only noise he could hear was the bell.

Then everything came rushing back on Nagisa at once, and he could feel again.

The young assassin shook his head to rid it of the ringing noise. He spent a minute just focusing on breathing before he even attempted to open his eyes. Nagisa looked up, blinking, at his surroundings and just stared at the sight before him in shock.

Everything was… normal.

Or relatively.

Nagisa was in the exact spot he had been just moments ago, or however long it had really been, trying to protect Kayano. But he was the only one in the clearing. No Yanagisawa. No God of Death 2.0. No concerned 3-E classmates. And no Koro-sensei.

Am I dead? Was the bluenette's first thought. And it was the most logical explanation. He had just been impaled by a tentacle moving at Mach 40. But had he really? Nagisa didn't remember feeling the impact.

The young assassin paused for a minute and realized that his back was a bit sore, but he didn't seem to be in any excruciating pain or bleeding out. Well at least that was one less thing to worry about.

But it did raise the question of what had happened? And was Nagisa dead, in a coma, or something else? After a year of being part of an assassination classroom, Nagisa had learned to just accept any weird thing that was now a normality of his life.

The bluenette slowly pulled himself onto his feet and truly looked at his surroundings instead of just a quick glance. The moon was normal, or well the crescent that Nagisa had come to expect. The clearing appeared to be in order, but it seemed like it was darker than before, like there was less light or something.

Light.

Projection.

Shield of Earth.

The Shield of Earth wasn't up.

A thousand questions started racing through Nagisa's mind. Why isn't the shield up? Am I in an alternate universe where it doesn't exist? Am I dreaming? Am I in a coma?

Nagisa turned around to look at the 3-E building and gasped in surprise when he saw there was a light on in one of the windows.

And in that room… Was Koro-sensei.

An idea started to form in Nagisa's mind. An idea the young assassin didn't like, but he had to be sure…

Nagisa fumbled for his phone and ignored the way his breathing sounded more like hyperventilating as he turned it on and checked the date.

March 6, 20XX. 7 days before the deadline to kill Koro-sensei.

Nagisa inhaled sharply, not wanting to process what this meant.

"What the f-?"

This is a sort of preview for an idea that I have, and if you guys seem to like it, then I'll continue. If you couldn't tell, it's a time travel au.

All canon dialogue is taken from the English dub, and I do not own Assassination Classroom.

Feedback is accepted and encouraged. Uh thanks for reading, and have a great day!