𝔐𝔶 𝔏𝔦𝔱𝔱𝔩𝔢 𝔐𝔬𝔫𝔰𝔱𝔢𝔯 (a xreader)

chapter 32~ birthday boss battle

I placed a drop of iodine in my test tube and the color changed from blue to yellow. "I...I...I DID IT!!" I cheered and sealed the antidote. "Koro-sensei is save." I said and my vision blurred for a moment. I shook my head. "Not the time to get weak." I muttered and looked at my phone through all the missed text messages from my friends. "Looks like they's planning to got through the mountain." I said to myself and looked at my camo combat suit from Class E that was hang in my closet. I quickly put it on and place the antidote in my pocket then the syringe in my pouch on my thigh. I used my speed to make it to the mountains. I noticed my friend fight one of the best men on the force. I appeared in front of him and kick him in the face. "Am I late to the party?" I asked and winked. "[Y/n]" "[Y/n]-chan..." "I couldn't just sit home and let you guys have all the fun." I said. "You punks...If you'd only behave, this'd all be over. What in blazes are you objecting to this late in the game?" He said and I glared. "This is our business!" I shouted and kicked him. The man flew back into the tree. "And you assholes need to stop butting in!" I yelled and tried to punch him, but he dodged it. I left a dint in the tree. Terasaka tackled the man, but the guy headbutt Terasaka. "Just let us handle this." An anti-sensei knife was thrown next to the man and Nagisa came out of nowhere and clapped in the guys face, leaving him stunned. "Karma." Nagisa called as he forced the man to look up while Karma kicked him in the face. The man was out cold. Karma and Nagisa gave each other a high-five. "Nice work, Nagisa." I said. "[Y/n]-chan, what are you doing here?" He asked. "I wanted to join the fun, and I made a promise to Koro-sensei." I said. "Hey! He's still moving!" Kayano said. "You damn brats!" The guy yelled and Terasaka and the rest of the class used their tasers. "Finish off right, you dumbasses! You can keep your show-off high-fives!" Terasaka yelled.

~~~

Soon we made it to the old campus and saw Koro-sensei. "I could tell by the sound." Koro-sensei said. "You've come this far, class." Koro-sensei said and we all ran over to him. I looked up at the sky. 'That's the laser, huh? We still have three hours.' I thought. "[Y/n]-chan?" Koro-sensei called and I turned to look at him. Koro-sensei hit me lightly in the head with his tentacle. "Stop putting yourself in danger with this." He said and I sighed. "Danger? What danger?" Kanzaki asked. "With particular experiment, it puts strain on my body and it could kill me." I said and coughed up a little blood. I forced a smile. "But I'm fine. Everything'll be fine." I said and my vision blurred again. 'Why now? Please just a little longer.' I though

Everyone gathered around the cake and Koro-sensei to sing Happy Birthday. "How about [Y/n] sing a song first?" Kayano said. "Eh?" "Koro-sensei really enjoys her singing." Kataoka said. "Wait what?" I said. "Do it!" They cheered. I sighed and used Ritsu to play music.(play music you want to-snatcherisnowblu)

Everyone clapped and we sang happy birthday. Koro-sensei was about to make a wish and blow out the candles until the cake was destroyed. "Happy Birthday." I heard Shino's voice, aka Shiro. I glared. 'He never listens.' I thought to myself. "The time is ripe. Let me give you the gift of the world's cruelest death" He said. "Sensei....you know who I am, don't you?" The person next to him said and began to unzip himself. "Why don't I reintroduce him--to your students, too. He's the man who stole the name 'the Reaper' from that octopus. And...as of today, he's the new Koro-sensei." Shino said. "It was the ugliest thing I've ever seen. Reaper 2.0 jumped in the air and landed on the roof of the old campus. "Before it was just his face, now his whole body is a monster." Muramatsu said. "He's just had the same modifications as that octopus The only diffrence is that he begged for them. Completely unlike the botched Itona or my little sister over there. Can you even imagine? A man that singlehandedly overpowered you even as a human now has both incomparable tentacles and hatred. The destructive power....!" Shino said and Reaper 2.0 punched Koro-sensei. The impact sent me and my classmates flying. "His tentacles have an initial velocity of Mach 2. And they can reach top speed of Mach 40." Shino said and Reaper began punching Koro-sensei at Mach 40 speed. "No! Sensei!" I called. "Stay back!" Koro-sensei yelled while Karma and Maehara held me back. My eyes widened as Shino put a syringe in his neck and began changing into Koro-sensei. "Koro-sensei!" I yelled and he was knock to the ground. "Class...There's something I forgot to mention in my earlier lesson: Even assassins who cleverly avoid head-to-head battles is sure to have a number of times in life when he or she have to fight with every last ounce of strength. In my case...that would be now!" Koro-sensei said.

~~~

As the Reaper and Koro-sensei fought, there was a sonic boom with every attack. The only thing I knew was that Koro-sensei was losing. "Sensei!" I said. 'Sensei, please...Fight!...Fight!...' "FIGHT BACK, YOU STUPID OCTOPUS!!" I yelled and Koro-sensei blocked Reaper's attack. Koro-sensei began dodging all of the attacks. 'He was studying the attack? Amazing.' I thought to myself. "This is where I, his teacher, take responsibility for my pupil who's strayed from the path. However...Yanagisawa. Leave us. This is a place for students to learn and grow. You are not entitled to be here." Koro-sensei said. "Still fancy yourself a teacher, huh, guinea pig? Then let's put you to the test. Don't you see why we chose this moment to make our move?" Shino said and the Reaper appeared in front of us. "You'll protect them, right? Isn't that what a teacher does?" Shino said and the Reaper shot electricity towards us but Koro-sensei blocked it with his body. As the smoke cleared, Koro-sensei was badly hurt. "Sensei....Sensei...." I began remembering the good time and the bad moments with Koro-sensei. 'I'm truly sorry, [Y/n]-chan.' 'Do your best.' He did it again and again. "Yanagisawa! Don't drag these students any deeper." Karasuma said and Shino used his Mach 20 speed to hit him. "Shut up and watch, government lapdogs. You can't stand a chance against me." Shino said and I felt something inside me snap. "[Y/n]?" Karma asked. "Let go." I growled and glared at him with my blood red eyes. They both back away. My heart rate and breathing began to increase. "How dare you...TOUCH MY FATHER!" I yelled as a dark aura around me grew and fangs grew out of my mouth. My eyes turned completely red and my nails grew sharper. The pain was extreme, but I had to deal with it. "For my sensei, my father, and my friends..." I said and laughed demonically. "I will....kill you." I said. Shino chuckled. "Yes. Show everyone the monster you truly are." He said. By studying their moves, I think I could use Mach 40 speed. I appeared behind Shino and kicked home into the air. "[Y/n]-chan....stop." Koro-sensei said. My eyes softened. He knew about this experiment and how it could kill me. It'll slowly drive me insane, leading to a painful death. But it's worth it to save my friends, family, and teacher. "Just....let me protect you for once." I said and jumped into the air. I suddenly felt a sharp pain in my side. "Good bye." Shino said. "You...dirty...bastard." I said and fell to the ground. 'That asshole stabbed me.' I thought and I gripped my side to stop the bleed. I checked my pocket and saw that the antidote was still okay. I coughed up a lot of blood.

~~~

I was woken up by a bright light. "What...what is that?" I asked. "It's Koro-sensei...he's going to make our graduation peaceful." Okuda said with tears in her eyes. "N-No." I said and quick stood up, ignoring the pain shooting through my body. And the stab wound in my side was not helping. "[Y/n]! No!" "Baka!" I ran down the small hill to Koro-sensei. I inserted the antidote into the syringe, but my body gave out half way there. I was able to protect the antidote, but not my body. I coughed up a great amount of blood. I could feel the madness spread to my brain. After the light, cleared Koro-sensei landed in front of me. He sat me up where I was facing my class. My eyes widened in horror once I saw the dead body in Nagisa's arms. "Kayano...-chan." I said and Nagisa handed her over to me. Tears filled my eyes as I hugged her cold corpse. She was my first friend ever. I failed at protecting on of my best friends. "Class, the past you've lost will never come back. I myself have made so many mistakes. But we can learn from the past so we don't repeat it." Koro-sensei said and a reddish-orange orb was floating in the air. "Huh? Wh-What is this?" Nagisa asked. "Kayano's blood and somatic cells. I gathered them up before she fell to the ground with compressed air." Koro-sensei said. "I-In the middle of battle?!" Nagisa asked. "I'd set aside tentacles meant for protecting you. Those were the only ones I didn't use for fighting." Koro-sensei said and took Kayano away from me. He began healing her. "Now to string all these cells together, one by one." Koro-sensei explained. Soon Kayano was alive. I smiled. "Kayano!" Me along with everyone else cheered and hugged her.