Human Koro-Sensei x reader

Seeing You Again

It's been about a month since Ai was born.
I thought it would be nice to visit the E-Class. See Nagisa and this monster they call a teacher and target.
Ai giggles while I get him dressed.
I pick him up and walk to the school.
It's a nice way to burn the rest of my baby fat.
When I get to the school I walk inside and through the halls.
I come to a door that has an E-3 sigh above it. "I guess this is it," I whisper.
Ai smiles sucking on his fingers.
I open the door slowly and walk inside. "I'm sorry Tadaomi for interrupting class."
Everyone looks at me.
"It's fine. You can take a seat in my chair." The stoic man replies pulling out his chair.
I sit down smiling. I set the car seat I carry Ai in on the ground. I take him out and he giggles.
"Um professor is that your wife and son?" A blonde girl asks.
I giggle. "I don't think that man could ever get married. He's too much of a workaholic." I respond. "No I'm just his best friend. I wanted to see Tadaomi in action as a teacher. And see a couple people."
"Hello aunty," Nagisa greets smiling.
I smile back at the blue haired boy.
"We were just about to go change for PE class." Tadaomi says. "Go change class and meet me on the field."
I stand up and hand Ai to the dark haired man.
Tadaomi holds Ai close smiling ever so slightly.
Ai giggles burying his head in the man's neck.
We walk out to the field and wait for the students.
Nagisa was the first one out and he hugs me. "I missed you aunty."
"I missed you too."
Once the kids are all out I play with Ai as the older man teaches the students.
It was pleasant to watch my best friend.

When they were done we walk back inside.
The students were already in their seats when I walk in.
I look at the teacher and he turns to me.
He stops dead in his tracks and his face turns white, then blue.
"Is something wrong?" I ask sitting down.
Ai giggles reaching out to the monster.
"Oh yeah. Koro-sensei if you don't mind I'd like to give my aunt a gift." Nagisa stands up and walks over to me. He bows giving me a small wrapped present.
I smile taking it. I open it and giggle softly. "I'm sure he will love it." I show Ai the picture frame containing the picture of the three of us.
It seemed to be the happiest day of Nagisa's life.
I kiss the boy's cheek and he hugs me.
My name is stuttered quietly from the monster's lips.
I turn to him still smiling at the photo.
His eyes widen and his face goes extremely dark blue.
"Koro-sensei what's wrong?" The students ask in unison.
My face saddens as I look at the yellow being. "Am I distracting everyone? I'm sorry sir I just wanted to visit."
"Do you know her Koro-sensei? Or did Karasuma tell you her name?" A green haired girl asks.
"I've never seen him before sweetie. Tadaomi must've told him." I respond.
All of a sudden I was outside with Ai still in my arms.
"What was that for?" I ask softly.
His tentacle moves hair out of my face. Then he puts my hair up, but only in a way my husband once did.
It was an inside joke.
My eyes widen. "How did you..."
"Ai," he whispers.
Ai giggles and falls into the monster's arms. "D-daddy!"
My eyes widen more.
We had picked out the name if we ever had a child.
"It's me baby girl. Karasuma didn't tell me anything."
"What happened to you?" I ask as tears water my eyes.
"I was captured and tested on. Finally I transformed into this and the moon blew up. By next year I will take the Earth with me. Unless this class can kill me first." He explains and looks into my eyes smiling sadly.
I gasp in realization. "You blew up the moon because you became this, not because you wanted to. You'll die next year won't you, that's why you want the kids to kill you."
He nods as Ai plays with his father's tentacles.
I turn to see all the children at the windows watching. "They don't know yet."
He shakes his head. "No. But I do believe it will come up later. I will have to tell them my past and what happened."
I place my hand on his cheek, like I always did.
He leans into my palm and turns to look at me. "I love you. I always have. I'm so sorry I left you." He kisses my forehead and smiles softly.
"I'm sure that instead of killing you, they could save you." I whisper hugging him.
Ai latches onto me and I hold him close.
I stare into his eyes and nod. "I will cure you."
He shakes his head smiling. "You should pretend to be Karasuma's wife and son. That way you can be here all the time. I'll stay with you at night. He can only have you during the day."
I laugh at his suggestion. "That sounds fun. Let's go talk to him." I walk back inside and my husband follows. "Tadaomi," I sing song walking to the teacher's lounge.
My husband opens the door and I walk inside. He closes the door knowing all too well his students would trying listening in.
"What is it?" He questions typing on his computer.
I take it and type the basic info and show it to him.
His eyes widen then he looks at us.
"So we were hoping you could pretend to be my husband and baby daddy. Just until he tells the kids the truth."
"I have no cure so they have to kill me." Koro-sensei informs. "She thinks she can come up with one but just in case she can't."
Tadaomi sighs but agrees.
"You will be subject to some emotion. I will kiss you in front of the kids to make it believable. And darling you can't get too jealous."
I look at my husband and we giggle.
"Then let's begin." I smile holding Ai close.
"But first you have to tell the children you lied. Now that we're together."  Tadaomi informs.
I bite my lip. "I have the perfect idea."