The retrieval of the tentacle cells went off, surprisingly, without a hitch. The security at the bunker went along with the Attack team, fully oblivious to their malicious intentions. And under Chiba's instruction, the Ministry of Defense received a professional evaluation of the bunker's structure, which was in great shape.

The Attack team was back at the 3-E classroom, tentacle cells in hand. Class 3-E was gathered to witness the moment. Okuda and Takebayashi grabbed the materials and set about double-checking their authenticity.

"So, how long until you guys test me?"

Everybody looked at Nagisa solemnly. This was the part where Nagisa threw away everything he had for his teacher.

"Not so fast." Okuda broke the silence.

"First, we have to find a way to remove the tentacles safely. Unlike Koro Sensei, we can't perform surgery at Mach 20, so tentacle removal will be dangerous for the party responsible. Also, we need a way to shield tentacle beings from the Shield of Earth."

Nagisa nodded. "I assume you need somebody to test out the removal surgery on?"

Okuda bit her lip. "I know you signed on for this, but experimenting on a human being still feels wrong."

Nagisa shrugged. "Then don't think of it as experimentation. Think of it as a clinical trial of new procedures"

"How is that better?"

"It sounds better. Anyway, I'll have to teach a new class again soon, so if you could be prompt that would be nice."

Okuda looked at Nagisa critically. "Once you go back in time, you'll have to wait nine years before you teach another class."

"So? I'll still be able to teach. I'll just be a little older."

Okuda sighed. "It's a little annoying how optimistic you are. But c'est la vie. If you're still on board, there's no time like the present. Everybody here will be equipped with anti-sensei weaponry of course. Just in case."

Nagisa nodded. He went and sat down at his desk. Okuda passed out knives and guns emblazoned with the letters S.A.A.U.S.O.

"You ready?"

Nagisa nodded. Okuda injected him with one of the tentacle stem cells, muttering about how, 'we really should be doing this in a lab,' and 'we need a way to dispose of this; it's technically a biohazard,' and, 'I cleaned this needle, right? God, I hope so."

A tentacle sprouted from Nagisa's neck. What do you want to be?

Nagisa ignored the question and looked around. Everybody appeared to be moving in slow motion now. He tried out his new tentacle by flexing it and bending it. He could change its color too. His friends hadn't moved an inch in the time it took for him to test his tentacle.

What do you want to be?

There it was again. Nagisa knew it wouldn't stop asking. He began to consider. What did he want to be? He had answered that question before.

I want to be a teacher.

The tentacles stopped speaking to him. His friends still hadn't moved. How do you go back to regular perception?

Nagisa focused on bringing his human senses back.

Okuda looked at him awkwardly.

"So, any homicidal impulses?"

Homicide? If anything, I want to protect people. Protect my students... Like Koro Sensei did.

"Nope. I'm actually feeling pretty good. You all look like you're moving in slow motion though..."

Okuda's eyes lit up with the spark of curiosity.

"Interesting. Presumably, that's just perspective. Now, do you mind trying out your new tentacles?"

"I already flexed them and such. What else do you want me to do?"

Okuda considered. "Would you mind trying to dodge attacks from us? It would help determine the extent of your abilities."

Nagisa nodded. "Whenever you're ready."

Isogai and Maehara launched into action with their anti-sensei knives. Nagisa had gotten quite good at dodging attacks between training and his students making attempts on his life, but now it was child's play. He saw all attacks coming at him in slow motion, and either used his tentacle to redirect or stepped out of the way. BBs were a little harder, but not very.

How did we ever hit Koro Sensei? This is easy at my speed, and he was faster! I'm surprised he isn't still alive...

Nagisa's assailants eventually tired themselves out.

"Taking role will be a lot easier from now on."

The rest of the class stared at Nagisa.

"Well, this is just like old times!" Everybody stared at Karma.

"What? This was pretty much Class E."

Kayano piped up. "Hey, if we really want to relive old times, why don't we try out the pitfall trap I made on Nagisa? It's still there!"

"That'd be a great test of your abilities! Let's go Nagisa!"

Nagisa started backing away from his classmates. "Yeah, I kinda don't want to break my legs."

Itona pressed a button, opening a trapdoor below Nagisa's feet.

"I made a trapdoor too, you know."

Nagisa cushioned his fall with his tentacle, then used it to pull himself up and out of the hole he had fallen into.

"Thank you very much for respecting my opinions Itona."

Itona smirked. "Anytime."

Karma stepped forward to examine Nagisa's tentacle. "Pretty sleek Nagisa."

Karma reached out to touch Nagisa's tentacle. It melted on contact. It didn't hurt much, right about the equivalent of a papercut.

"Another one bites the dust. Are all tentacle beings this dumb?"

Nagisa's tentacle regenerated quickly. He used his tentacle to rifle through all the girls' bags at Mach 20 speed until he found what he was looking for: a makeup kit. He had done makeup before for his students, and that experience came in handy. He did Karma's makeup as quickly as he could and returned the makeup kit to its owner.

"Do you always look this nice when you attack a tentacle being?"

"What does that mean?"

"By the way, thanks for the loan Kayano."

Kayano smirked. She still had some of the kinetic vision from her time with tentacles, and as such had seen what Nagisa had done.

"Anytime. I have a hairbrush too if you need it."

Karma's grin faded. He pulled out his phone and used it to look at his reflection.

"I will jump off that cliff."

Nagisa grinned. "And I will catch you."

Nagisa's tentacle, blue previously, was now wrapped in green stripes.

"Hey, don't get cocky. I might just kill you."

Nagisa looked down at his tentacle. He willed it to return to its previous color.

Okuda cut into the conversation. "Speaking of color changing, do you mind trying out your camouflage Nagisa? For now you can just try color matching to the classroom."

Nagisa nodded. He held his tentacle against the wall and focused on matching it to the wood. His tentacle disappeared into the wall.

"Wow, I can barely see it!"

Okuda scratched in a tiny notebook. "Alright. It looks like we won't need to remove the tentacle after all. Now, we need to turn you into a full-on tentacle being if we want this to work. There are two ways to do that: we can either recreate Yanagisawa's experiment, or try to find a way to do it with the tentacle cells we already have."

Nagisa shrugged. "I'm good with whatever works."

Takebayashi mused to the group. "Yanagisawa's experiment was noted as unethical by Koro Sensei. I don't think he'd approve of us recreating it."

Okuda considered. "And just to make sure, you're still okay with this, right Nagisa? Because once we tentacle-fy you, there's no going back as far as we know. We'll work on it of course, but we can't make any guarantees."

"I can still teach if I look like an octopus monster. Besides, I'll have a good deal of time while I wait to come back to the present day. I can always work on it in my spare time."

"If that's what you intend to do, we'll send you back with all our findings and keep you up to date while we work."

"That would be much appreciated. In the meantime, how do I become a tentacle being in the first place?"

Takebayashi articulated a theory. "If we inject enough tentacle cells into your bloodstream, they'll be carried all around your body and take root in vital areas, thereby fully transforming you."

Okuda nodded. "That could work. Do we have enough cells?"

Takebayashi opened the case retrieved by the Attack team and counted.

"Just barely. We'll have to inject directly into his vena cava though."

"That could kill him!"

"If it works, the tentacles will allow him to regenerate. If not, you're right, he will most likely die."

"Is that a risk we want to take?"

Ritsu joined the conversation.

"I calculate the odds of success at fifty percent."

Okuda's temper flared. "We can't leave Nagisa's life up to a coin flip!"

Nagisa cut in. "Koro Sensei once calculated his chances of survival at fifty percent. He took that chance to save Kayano's life. I will gladly take that chance to save his."

Okuda glared. "At least inject it into the inferior vena cava. Then we'll have more time to save him as he's paralyzed and his chest cavity fills up with blood."

Takebayashi nodded. "That would be wise. Do you mind helping me put all the stem cells in one needle? Oh, and we need to strap him down to a table."

"And just to be sure, you still want to go through with this, right Nagisa?"

Nagisa nodded. "I'll take the chance."

"Alright. If you're sure, I'll go through with it. Now, you'll need to be secured. We can't risk you flinching when we inject the cells."

Ritsu waved one of her robotic arms. "I can hold Nagisa down. I'll be a good deal more secure than standard operation tables, and you can sterilize me pretty easily."

Okuda nodded. "Alright, somebody needs to wipe Ritsu down with isopropyl alcohol. Be thorough! If this fails, Takebayashi and I will need to improvise heart surgery, which is hard enough without the wound getting infected."

"Actually, I won't be improvising. I had a position in an ER for a while, and I had to do heart surgery on a guy with a gunshot wound to the pulmonary artery. It was difficult, but the guy is alive."

Okuda looked impressed. "Wow, really? No wonder you've advanced so fast. Between that and fast-tracking your doctorate it's no wonder you're already famous in the medical field."

Takebayashi shrugged. "It was mostly luck."

"Nevertheless, you have experience, and that's a good thing. What did you use?"

"Clamp, needle, thread, scalpel. All sterile."

Okuda nodded. "We shouldn't go through with this until we have all of those materials on hand."

Takebayashi held up a small bag with a red plus on it. "Never leave home without it."

"Good. Hara, you have Ritsu wiped down?"

Hara nodded. "All clean."

"Alright. Nagisa, if you don't mind."

Nagisa strolled over to Ritsu and held his arms up for her to grab. Ritsu clamped Nagisa around the wrists, neck, hips, and ankles.

"Nagisa is secure."

Nagisa shook his head. "No I'm not. Somebody needs to hold down my tentacle."

"I'll do it."

Tersaka stepped forward and grabbed the blue tentacle.

"I've had plenty of practice grabbing Itona's tentacles. Given that was eight and a half years ago, but what're you gonna do?"

"Here, I'll help."

Karma opened the door to the classroom. He had left to get the makeup off, which he had done quite thoroughly. His face was still slightly wet from washing his face in the bathroom.

Nagisa checked Karma's hand for knife slivers. Good, he's clean.

Karma grabbed his friend's tentacle.

"For the record, if you ever do makeup on me again, I will personally see to it that you die a horrendous and painful death."

Nagisa chuckled. "Don't worry. I'd much rather do your nails instead."

Karma glared.

"Break it up you two. We're kind of about to potentially do heart surgery, so it'd help if we didn't have to keep the two of you from fighting."

"By the way guys, if I die-"

The entire class silenced and held their breath

"Would you mind teaching my class next year?"

E Class chuckled.

"We will. We promise."

"Right then. Shall we?"

Takebayashi cut off the black t-shirt Nagisa was wearing. He then grabbed a large needle chock full of tentacle cells.

"Hold him steady Ritsu."

Ritsu's image nodded. Takebayashi jammed the needle into Nagisa's chest and pushed the lever down. Tentacle cells flooded into Nagisa's heart. He started trying to convulse, but Ritsu held him in place. Takebayashi pulled the needle out and set it down, ready with a scalpel for the worst case scenario.