The Reaper, the world's greatest assassin, finally understood the value of life only when he held her dying body in his arms.
It was a fatal wound. Even the Reaper, a cutting-edge expert in medical science, couldn't fix it.
The lab he had destroyed. His body was changing by the moment. He noticed none of it.
All he could ask was why.
"Why…? If you hadn't jumped out, you wouldn't have gotten caught up in my mess…"
Yukimura Aguri, on the verge of death, still managed a weak smile.
"I was careless… I never imagined there'd be a trap like that… but… I figured that just shouting wouldn't be enough to stop you."
The Reaper knew she was exactly right.
If he had entered the outside world in that state, his distorted emotions would have distorted his tentacles, and his distorted tentacles would have distorted his emotions. He had been on the verge of becoming a dark creature of destruction.
What had brought him back was her touch.
I could have protected her if I'd noticed just a tenth of a second earlier. I could have saved her if I'd only practiced using my tentacles for precise medical treatments.
The assassin had grown up hating the world. Everything he had gained had been used to destroy his opponents.
Scientific knowledge. Combat skills. Communication. The tentacles.
And now he understood that there had been other ways to use them.
Why…? There was plenty of time to notice. My power to kill, my power to destroy, could have been used for the sake of others. Why? Why?!
In the end, all he could do was admit the truth.
"It… it might as well have been me who killed you…"
Aguri reached out. Her smile remained as her voice grew weaker.
"No… you know that's not true. I moved because I wanted to. And also… as long as it's for your sake, I'm perfectly fine with getting killed… That's how precious you are to me… One day, you'll meet someone you care for like that, too."
The Reaper looked at her as if that were impossible.
"I wouldn't regret letting myself be killed for your sake. But… I don't think there's anyone else like that out there for me."
Aguri looked at him. His body was becoming less and less human. Even the hand holding her had turned into a tentacle. Her time was running out, but she still had one last thing to do.
"If… you have only one year left… if you would give your time… go teach those children. Just like you, they are lost in the dark… Look them straight in the eye… and I know you'll find your answer."
The Reaper, who looked like a man who had lost everything, finally found something to hold on to. He smiled faintly at her.
"…If you say so."
Aguri smiled back. With the last of her strength, she squeezed one of his fingers, which had already become a tentacle.
"What… lovely tentacles… With these hands… I know you'll be… a splendid… teacher."
Her hand finally let go. Her eyes closed for the last time.
In the pocket of the former teacher lay the birthday present she had chosen for him.
An enormous necktie. The kind he could never have imagined wearing.
He held it tightly.
"So lame."
He understood now that this flaw of hers was just another part of her charm.
With that, he made his final promise.
"So long as I still have time… I will use it as a teacher. I will keep looking, with my own eyes, at the students you've been watching. No matter what, these tentacles will not let them go."
Sensing someone approaching, he touched her face one last time before flying away.
He moved at tremendous speed. His human cells were completely replaced by tentacles, and he was reborn as an entirely new life-form.
With this power, he could do anything. What kind of creature he became depended on his desire.
The tentacles asked him.
"What do you want to be?"
He answered.
"I want… to be weak. To be riddled with weaknesses, easy to talk to… to be able to perceive the weak, protect them, guide them… to be that kind of creature… that kind of teacher. Sometimes I'll be wrong. Sometimes my cold-hearted true self might even show. But I'll give it my all. I'll pursue her goal in my own way, the way I do best."
---
Koro-sensei finished.
"This is all about my past."
No one knew what to say.
He continued speaking like a teacher.
"Now it's time for everyone here to ask about anything that remains unclear or seems suspicious."
Not a single student doubted his story. Not even Kayano, who was silently crying.
Everything fell into place. Even the fact that he possessed so many skills. Even the way he avoided assassinations as if he already knew they were coming.
And not a single student intended to blame him for Yukimura-sensei's death. Everyone knew that both of them were teachers who would never leave someone in trouble behind.
Koro-sensei continued.
"The one who taught me to be a teacher was Yukimura Aguri-sensei. To truly look at the people before you and respect them as equal human beings, rather than judge them solely by their weaknesses… I learned the fundamentals of being a teacher from her. I added my own knowledge and experience and prepared to face you all. I would use my abilities to the fullest to give you the gift of the best possible growth and development. But how best to do that? I racked my brain… racked my brain… and finally settled on an assassination classroom, where I could use what remained of my life."
That was exactly how the plan worked.
Kill.
Dodge.
And teach.
Through an education based on assassination, the darkness in their hearts had gradually cleared.
Koro-sensei looked at them.
"As I have already told you, the bond we have created between us is that of an assassin and his target. If we weren't an assassin and his target, I could never have become your teacher. And if we weren't an assassin and his targets, you would never have earnestly clashed against me. For this very reason, this bond, this class, can only be completed with an assassination. Even if an outsider assassin kills me. If I surrender and they execute me. If I commit suicide… or if my time runs out and I explode."
His eyes moved across the class.
"In any of those cases, my life will be over, and our bond will be severed before your graduation. If I have to be killed… at least I want to be killed by you, not by someone else."
The difference in power was too great. Because of that, no one in Class E had ever truly considered what it meant to kill him.
All their memories came rushing back at once. The time they had spent together.
The frightening times.
The infuriating times.
The happy times.
The fun times.
The fun times.
The fun times…
Now, for the first time, they realized the formidable challenge they had set for themselves.
Do we really have to kill this teacher of ours? Can we even do it?
No one had the answers. Even Karasuma and Irina turned their faces away.
After all, what did it really mean to kill someone? Each person had to find the answer for themselves.
And just like that, winter vacation arrived.
Akira sat in his lab, deep in thought.
Not about Koro-sensei's backstory. He already knew that.
He was thinking about his own problems.
What was that black gate?
What did it mean for it to be here?
What was going to happen to this world?
Something like that had never happened in the original story. Not in the manga. Not in the anime. Then again, he didn't know the ending, so he couldn't be completely sure.
But he had a feeling. This mission wasn't going to go according to plan.
Selena was conducting her own research but hadn't given him an answer yet.
Akira remained lost in thought, running calculation after calculation as he tried to figure out what it was and what might happen next.
Because of that, he didn't notice Erika coming down from above, carrying some refreshments.
Erika looked at Akira.
He was completely lost in thought. He had been like this ever since he connected with Kayano's tentacles yesterday.
When she asked what had happened, all he told her was that something serious had occurred, though he didn't know exactly what. Selena was looking into it, too.
Since then, he had spent most of his time like this.
Gone.
She called out to him.
"Akira. I brought you some hot chocolate."
"Uh-hmm."
He didn't say anything else.
Erika pushed the cup toward him.
"Here. Drink it while it's hot."
Akira took the cup without really looking at it. He didn't drink.
He was still completely lost in thought.
Erika sighed, took the cup back, and started feeding him. He drank slowly, his mind still somewhere else.
She was a little frustrated. She knew he wasn't deliberately ignoring her, but it was still frustrating.
Then she remembered something.
Hadn't Akira always been like this when they were children? Constantly lost in his own world. Magic training. Making something. Back then, she had to drag his attention back to her by clinging to him until he finally responded.
She had almost forgotten about that.
After they became a couple, he had been the clingy one, acting as if his entire world revolved around her. She had been really happy about that.
Now she realized he had always been the same. She had simply become a bigger part of his world, but he was still the Akira she had always known.
She didn't really know what to do. He was busy with something important, so she couldn't disturb him. But she was lonely, too. He used to stick to her for a few minutes every hour. Now he wasn't doing that anymore.
It's all this idiot's fault. Why did he suddenly stop clinging to me?
Then she made up her mind.
Fine. If he won't cling to me, I will.
That was what she had done before they became close, after all.
She sat next to him.
Closely.
Then even closer.
He barely reacted.
She leaned her head against his shoulder.
Then she started leaning her entire body against him.
Akira still said nothing. His eyes remained fixed on his calculations.
Seeing that, Erika grew bolder.
She wondered what she could do before he finally noticed her.
She stood up, sat on his lap, and leaned against him.
Then she turned around and wrapped her arms around his neck.
"Idiot. Just you see what I'm going to do to you."
She picked up her makeup set and started playing with his face, making him look as beautiful as possible. Only after she had made him pretty enough to rival even Selena did she nod to herself, feeling rather proud of her skills.
He still wasn't reacting.
But as she looked at his beautiful face, a traitorous thought suddenly popped into her mind.
She leaned closer and closer, wondering if she could sneak in a kiss.
Just as her lips were about to touch his cheek, Akira finally snapped out of his thoughts.
He looked at her, clearly confused.
"Erika. What are you doing?"
Erika turned bright red.
"Ahhhhhhh!"
She tried to get away, accidentally headbutted him, and fell over.
Akira held his head.
"Ouch. What was that about?"
Erika flailed her arms.
"It's nothing! It's nothing!"
Akira stared at her in confusion.
"Why are you sitting on me?"
Erika snapped.
"I said it's nothing! Now stop talking about it!"
Akira looked even more confused.
"Okay. I guess."
Erika got up, collected herself, and asked, "So, what exactly happened? Can you tell me?"
Akira looked at her for a moment, still a little confused, before nodding.
"Selena has finished some of her research. We can talk about it. But before that…"
Erika looked serious.
"What?"
He gave her a strange look.
"Were you trying to kiss me?"
Erika turned completely red, shoved his face away, and snapped, "I was not, you idiot! Shut up!"