It was unusually cold for a day in March. Chiba tugged his hood over his head and zipped up his jacket. Crouching down, he loaded his sniper rifle and waited.

Hayami was freezing. She glanced over at where Chiba was hidden, wondering if it was just her who felt this cold.

Today was the day. It was their last chance to kill Koro-sensei. If they failed...the Earth would explode tomorrow, March 13. They had to succeed.

And this time, she couldn't miss.

Chiba peered through the scope, preparing for Koro-sensei to appear. Nagisa had put together the perfect plan, using everyone's strengths. All he had to do was play his part- one of the most important parts of the plan.

If he and Hayami missed...it was all over.

Hayami was shivering- and it wasn't just because of the cold. As much as she wanted to deny it, she was terrified to kill their teacher. But she was also terrified that she would fail. A flash of yellow appeared in her scope, hidden by the trees. She gripped her gun tighter, her finger hovering over the trigger.

Chiba was breathing heavily. His heartbeat racing, he quickly calculated how to angle his gun. Glancing quickly down at Koro-sensei to make sure that the trajectory he'd planned would work, he closed his eyes and squeezed the trigger.

Hayami immediately dropped her gun and looked down from her perch on the mountainside. The smoke from Okuda's smoke grenade was just clearing. She could see Karma's red hair, and near him, Nagisa's blue ponytails. Nowhere near them was any sign of yellow.

Chiba spared a quick glance down at where Koro-sensei had been before he looked over at where Hayami was hidden. Did they do it? Was their teacher dead?

"We did it."

Nagisa's voice carried up to her. Hayami's breath hitched when she realized that they'd succeeded. They'd done it. They'd killed their teacher. Below her, outside the classroom, there was a moment of silence. Then it erupted into chaos. She could hear Terasaka's group cheering, several other people crying. But she was paralyzed. She couldn't seem to process it.

Koro-sensei was dead.

Chiba pushed through the leaves, tears stinging at his eyes. Blinking them away, he made his way to Hayami's spot. He needed to make sure that she was okay.

"Hayami," he murmured, sitting down next to her.

She looked up at him. A tear traced its way down her cheek.

"We really did it, huh, Chiba?" she whispered.

Chiba nodded wordlessly.

"I kind of...I kind of wish we missed," Hayami admitted, her voice wavering.

Chiba just looked at her in silence. He knew that she knew what he was thinking. That it was for the good of everyone. That it was either the Earth or their teacher. That Koro-sensei would've wanted it this way.

"But I don't regret it," Hayami said, her tone confident, though she was still teary-eyed.

Chiba put his arm across her shoulders.

"Neither do I."

Hayami knew that even though both herself and Chiba had chosen the kill team in capture the flag, they both hoped that Koro-sensei could be saved. But it had turned out to be impossible. Even though the save team had won that game, their team won in the long run.

But she didn't feel victorious.

It's been four years since that day.

Chiba glances down at his phone upon its vibration. Isogai had asked everyone to meet at their old classroom after school.

Their last day of high school.

And now, before they leave to go to college, he wanted to see their classroom one last time. How could Chiba refuse Isogai's request? After all, he wanted to go visit their classroom, too.

Their assassination classroom.

Hayami waits at her locker, her backpack slung over one shoulder. In her hand is the necklace Chiba had given her for her birthday a few weeks ago. It's simple, a silver chain with a pendant shaped like a sniper rifle hanging on it. She rubs her thumb over the date engraved on it.

3/12.

The day they killed Koro-sensei.

Chiba stops at Hayami's locker. She smiles up at him, taking his hand. He notices the necklace she's wearing, and he smiles back. Taking his hand, she pulls him along to where their friends are waiting.

"Ready to climb up that mountain again?" Hayami asks, a bittersweet look in her eyes.

"As long as you're not too weak," he replies, a teasing tone in his voice.

She rolls her eyes and jabs him in the side with her elbow. "Let's go. They're waiting for us."

It's unusually warm for a day in March. The snow's even started to melt. But still, Chiba feels cold. As cold as he felt four years ago.

He kneels down, concealed in the leaves. Under his knee, under the melting snow, is a hard piece of plastic. He pulls it out and realizes what it is.

His gun.

The gun that he'd shot so long ago.

And suddenly he feels cold again, as he tugs his hood back over his head.

Hayami slips away from her classmates outside their old classroom. She makes her way back up to her hiding spot, where she'd shot Koro-sensei so many years ago.

But yet it didn't feel like it had been four years ago.

It felt like just yesterday when she'd crouched here, aiming carefully, and squeezed the trigger.

And she feels so very cold.