(Just a little bit about this before the story I gotta change Kiyokos name to fit in the naming scheme of the Saikis so meet Kuyoko.)
When your younger twin is a psychic things get odd.
Like right now even just walking home.
A truck was flying towards a dog and he stopped the truck from hitting it.Pov change
My name is Kusuo Saiki, and I have psychic super powers. While my sister beside me has none. Sixteen yeas ago an ordinary couple gave birth to a not so ordinary boy.
I started talking when I was fourteen days old without using my voice. Soon after I started walking when I was one month old, on the air. And at one year old, I ran my first errands. My mom finally started to worry about me especially sense my twin didn't do any of this. Now you'd think after a year of this they'd take me to get tested, but my folks are kinda weird themselves. Not to mention lazy. They can still act like lovebirds and they take everything in stride. Including me and all my weird powers. So time rolled on, I became the person you see now a high school student. As you saw with the floating car I still have my powers. I can bend spoons like any good psychic, and I can win any corporate giveaway I want. My life is a dream come true, that is what your thinking right. Well let me drop some truth bombs bending spoons makes it harder to eat, and winning free popsicles just leads to stomachaches. He's the happiest boy alive that boy can have anything and do anything, his poor sister. Well your dead wrong I'm the unhappyest boy alive a boy who had nothing. Telepathy, psychokinesis, X-ray vision, precognishion, teleportation, charvoince, etc etc. Sure I can do all those things...Pov change
'Kusuos stuck in his head again.
Oh look it's dad sitting outside the house.'
"Kuyoko, Kusuo welcome home my children. Your running kinda late today. I'll get right to the point kids. I'm locked outta house, cam you open it up for your old pops."
'Again.'
Then Kusuo opened the door with his psychic powers.
"Whow I love those psychic powers of yours, there just so sneaky yea. Kusuo with all those powers think of all the things you could do."
"Stop." I told him.
"Oh is that Ku your back." Mom said.
"Ahh we'll talk later!"
"Yoko I thought you had tennis practice?"
"Something came up with the coach, had to cancel." I say going up to my room to change and avoid the silly argument.I get called down for dinner.
'Is Kusuo still in his uniform.'
"Gorge yourselves guys I made a ton."
"Hey! Hey, Hey!" Dad said referring to the shoe of rice on his plate.
"Is it good kids?" Moms nice.
"Oh hey would you like something else." Wow this is good, she did great.
Dad started to bother Kusuo to change his shoe into a steak.
"Mom this tastes great."
"Oh thank you Yoko, your too nice. Hey Ku just remember what I've always said, just Don't use your powers for evil. But feel free to us your powers to hurt your daddy."
Then Dad started eating off Kusuos and my plate."Stop eating my babies dinners you theving son of a bitch! That's it we're taking this outside!" When will this stop.
Then they nock into my twin trying to eat his mature dignified jelly.
While I'm eating my red velvet cake.
Both almost fall but Kusuo eats his before it hits the floor, and I catch mine.
'Sorry mom but I might have to kill dad before you.'
"You wanted desert that bad. Forget the sweets we got biggest problems, your mothers turned into a monster!" And that's my cue to leave Sorry Kusuo your on your own.Pov change
'Rude' the psychic boy thought as the only normal member left.
Pov change and time skip
'Does anyone like school assembles?' Thought Kuyoko.
'No dear sister, no one does.' Replied the pink haired psychic telepathically.PK Academy a relatively small school, one might call it average or normal; buy it does have some odd students.
Like the blue haired seemingly glowing girl, or the enthusiastic buff red head one either side of Kuyoko.
So instead of actually paying attention she zoned it out.And then a human broccoli 'passed out'.
And the dumb yet somehow lovable Nendo started to beat up the passed out guy.
A teacher finally intervened and told him and Kusuo to take the trashy human broccoli to the nurse.And the boring assembly went on.
The bored students eventually got our schedules, took long enough.
Time skip
Kuyoko has strep.
That's all the psychic could think of while ge had to be at school while a snake is on the loose.
'Shame, my sister actually likes snakes. She might know the type, she could handle it.'Meanwhile
Kuyoko is extremely bored and annoyed.
Now she loves her mom more than anything, but she's really getting annoying.
But at least she means well.
"Mom."
"Yeah sweetie."
"I'm fine you don't have to worry so much."
"Your so grown up." And despite looking so happy and proud she looked sad.
"Mom."
"Hmm."
"Come here," the girl opened her arms for a hug. "You looked sad."
"My babies so sweet.""Hey Kuyoko Wana watch some TV while I do your hair, just like when you were so little."
"
The girl in question nodded her head yes, how could she say no to that face.So the two sat hours on the couch having some wholesome mother-daughter bonding time.
Sorry there's a lot of time skips but the way I'm writing it makes it hard to write other wise. Also if there's any grammar or spelling mistakes let me know so I can fix it, this also counts for later chapters.

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The Sister (Saiki k x oc kinda)
Fanfiction(Character insert) What if Kusuo Saiki had a twin sister, but she was normal. (This may seem a bit odd but think it's fun. Just like what if Kiyoko Shimizu from Haikyuu was in Saiki K)