Summary: This fanmade story occurred during chapter 173. A story focusing on that desperate moment when the Koro-sensei and the Class 3-E students were trapped in that "dome" together with the enemy.
Despair. It was the dominant feeling that the class 3-E students felt when they were trapped there. After devising a plan to escape, they were able to reunite with their beloved teacher, Koro-sensei. Their little reunion was interrupted by Yanagisawa and his "new weapon" which was later revealed to be the fake god of Death.
They helplessly watched as Koro-sensei fought against those two monsters. They know that Koro-sensei will experience difficulty defeating those two, but they are still faithful that a miracle would happen. Still, they also consider that Koro-sensei might not be able to win against them, especially if they're around. They've always known that they are their teacher's weakness.
"Even if Koro-sensei is well-experienced, it's too difficult for him to defeat the fake god of Death and Yanagisawa," Nagisa said while getting worried to their teacher.
"Yeah. Those two are so strong. Not to mention that part of their strength is due to their grudge at Koro-sensei" Kayano replied as she remembered her past self. Back then, she also had a grudge against Koro-sensei, whom she thought was the killer of her elder sister, Aguri.
"W-we need to think of a plan!" Manami said. But before anyone could respond to her, the next thing they knew was the fake god of death is about to attack them. But Koro-sensei took the damage in order to protect them from harm.
"Koro-sensei!," shouted some of the students. They tried to go near their teacher but was stopped by Karma.
"Stop! Going near him would only make things worst. This is a battlefield and Koro-sensei is trying to protect us." Karma exclaimed.
"He's right. We're his weaknesses," Itona said as they watched helplessly at Koro-sensei taking the fake god of death's several attacks.
Koro-sensei was telling the students that they were never his weaknesses nor his burden. In fact, they are his beloved students and he will even risk his life just to ensure they're safety.
As he was explaining this, another attack was about to hit him when suddenly, someone stepped forward and tried battling with the fake god of death.
Everyone was shocked to see Kayano defend their teacher from the dangerous monster. They were able to see Kayano's true abilities which she kept when she still had those tentacles.
"Go Koro-sensei. Go and heal yourself. I'll buy you some time!" Kayano shouted as she prepared to dodge the monster's attack. "... at least let your student protect you." Kayano added.
"It's funny how back then, I hated him so much that I wanted to kill him. And now, here I am protecting him after learning the truth about my sister, that Koro-sensei didn't kill her at all. At least this time, I want to repent for my sin of blaming him for her death." Kayano said to herself as she dodges the incoming attack.
She was able to dodge those attacks with her swift movements. This was probabaly an effect because she was once a tentacle user. She was about to stab the monster using her knife but was stopped by the monster's powerful attack. The next thing she knew, she felt blood dripping out of her body and her vision blurry. She heard Nagisa shout her name as she lay on the ground.
"Kayano!" Nagisa said as he held Kayano on his arms while tears run down his eyes.
"I-I can see Koro-sensei turning black. I must have a-angered him. Right, Nagi-sa?I'm s-sorry." Kayano replied weakly.
The other students tried running towards Kayano and Nagisa but was stopped by Karasuma-sensei who was also there. He tried stopping Yanagisawa but he failed and instead, took damage as well.
"Stop! That is exactly the middle part of this battlefield. Going there would only increase the casualties!" Karasuma-sensei said as he tried to stop the students. They students obeyed Karasuma-sensei since they knew that what he's telling is true. They watched helplessly as Koro-sensei fiercely fought those monsters who hurt his student and as Kayano bled to death.
However, one of the students didn't listen to Karasuma-sensei's warning and went to Kayano and Nagisa. It was Manami.
"Okuda!" shouted her classmates. They were worried with her as they watch her run towards Kayano. She was shocked when she saw that she is about to get hit by Yanagisawa's attack when a hand suddenly grabbed her away from where she's standing and was able to run faster.
"I never thought I'll see your stubborn side, Okuda-san" Karma said as he held her hand and run as fast as possible in order to reach Kayano and Nagisa.
"Karma-kun. I'm sorry for involving you. I just don't want Kayano-chan to die. She's my friend." Manami explained while holding back her tears.
Karma nodded. He knew that Manami would do everything if it's for a friend's sake.
"Treat her wounds while we try defending you." Karma said while giving a knife and gun to Nagisa. Nagisa wiped his tears and understood what he has to do.
"Please take care of her Okuda-san," Nagisa said as he took the knife and gun from Karma's hand. His expression was that of a dangerous assassin. Together, those two countered few attacks whenever Koro-sensei wasn't able to dodge it. Still, Koro-sensei was the one who fought those two monsters and they just supported him. They both knew that they cannot win if they fight those monsters by themselves. They knew that Koro-sensei is still protecting them as they fought. Still, they want to fight for their friends' sake.
Meanwhile, Manami was able to cleanse the deep wounds and applied some herbs that can stop the bleeding. She also added lavender oil so that the wounds would heal. She's worried about Kayano that's why she took that risk and she can't afford to fail in reviving her unconscious friend.
"Karma-kun and Nagisa-kun are taking risks by battling so that I could save Kayano from blood loss. I can't lose as well! Please survive Kayano-chan!" Manami said as she applied bandages and checked Kayano's pulse.
As the heated battle continues, Kayano felt a hand touched her forehead. It's warm. She wanted to touch it but she was too weak to move. When she opened her eyes, she saw someone smiling at her. She couldn't see her face due to the blinding light. That's when she heard the person's voice that she was able to realize who was beside her. "Akari!" It was her beloved sister. She's too relieved to see her again. She hugged her tightly. She missed her so much.
"I can't believe how you fearlessly fought. And I also can't believe that you would risk your life just to protect him. Just like what I did." Aguri said as she hugged her sister.
"You and Koro-sensei taught me to believe in myself" Kayano (or Akari) replied. "I'm so glad to be reunited with you."
"This is not a reunion yet. It's just farewell. Now, go, live, and have faith and courage my beloved sister" Aguri said as she let go of Akari's hand and everything went dark.
After a few minutes, Kayano can hear a voice. But this time, it wasn't Aguri's. It was her friend's voice, Manami who was calling out her name multiple times. She slowly opened her eyes.
"Kayano-chan!" Manami exclaimed while teary-eyed.
"Manami-chan, what happened?" she asked.
"We'll explain the details to you later. Right now we have to get out of here as fast as possible. It's too dangerous here." Karma said without looking at them. He was too busy defending from any possible attacks.
"Okuda-san, wait for Karasuma-sensei to get here and assist Kayano." Karma said to Manami. The bespectacled girl nodded.
Karasuma-sensei approached them quickly and led them to the door that was camouflaged in the dome-like barrier where Yanagisawa and the fake of death entered. Once the four students were outside, they were assisted by their classmates.
"I'm glad you're safe, Kayano. Or should I say, Akari." Nagisa said while assisting Kayano.
"Either way is fine." Kayano smiled. "Thanks for protecting us earlier." Nagisa nodded.
"But still, we're in despair. The battle between those superpowers continues. We don't know what the outcome may be." Nagisa said as he starred at the barrier.
"Just like my sister said, I have to live and have courage. In this time of despair, we need to have faith and courage." Kayano said as she stood next to Nagisa while watching the heated battle. Right now, what they can do is to have courage and to have faith in their beloved teacher.