Katsuki's New Sibling Life


"Katsuki..." Mitsuki started slowly with a warning tone. "This is your new adopted sister, (Y/N) Bakugo." "WHAAAAAAAAAT!?!?" Well, we all have our times as an older or younger sibling, maybe even somewhere in between. If you are an older-or the oldest-sibling, good luck! Not everyone has an older or younger sibling, not even Katsuki -well now he has one, and that's you. Adopted by the Bakugo couple, you now start an exciting life with the explosive, ticking time bomb known as your older sibling. Find out what trouble -or head aching- pranks, times and scenarios you will experience with the Bakugo family. This is a fanfiction of the popular anime, My Hero Academy and the story will circle around, you, the reader and Katsuki Bakugo, a hot headed 15 year old. I do not own the characters of My Hero Academy.

Adventure / Action
Shezdony Sprite
4.7 3 reviews
Age Rating:

Chapter 1: Orphan

You know, being a kid is great, you are loved, spoiled and fawned over by both teens and adults alike. And if you were an orphan kid, the one thing you’d wish for is a happy, loving family.

Though unfortunately for you, (Y/N), you don’t get to pick.

Date X, XX, 20XX, a year before the infamous sludge incident. In a city in Japan, where people of the future — with quirks and none—reside in, Mitsuki and Masaru Bakugo got a little tired with their explosive adolescent boy. He was no longer a kid and they missed that, so they decided to adopt a child.

Since that taking care of a baby is like having another Katsuki in the house, they chose a to adopt a 4 year old. Young but old enough for all to take care of —yes, even Katsuki has to take responsibility on looking after you.

You are a simple optimistic kid despite loosing your parents to a villain attack. Neither of your older siblings, who were aloud to take you in, place you under their care. And you can’t be sent out to of the country to other relatives, if you have any, they practically left you on the doorstep of an orphanage.

Fortunately, the orphanage you were in was a nice one, the caretakers were loving and the children were just honey. You’d blend right in!

Just a bit too well...

You blend in too well, that you were never adopted. None ever noticed you,surprisingly. Unfortunately the orphanage closed because the place got bankrupt, so the children were sent to other orphanages around the country.

Though, you were still a bundle of joy despite those harsh times, you were strong, the say and because of that you still continue to be.

One day, the Bakugo couple, Masaru and Mitsuki Bakugo, had taken a trip to an orphanage in the city. The reason for going to an orphanage is explanatory, they want to adopt a child.

And fortunately for the sake of the story, this orphanage in particular is where you are currently residing in!

The orphanage building was like an apartment, a home, sheltering other children who were victims of villain attacks, lost their parents by birth or in accidents or, maybe just left there like you.

Reflecting against the cream colored walls the sun’s soft rays made the building look like a mirror with lively chatter of children that can heard from inside, even at the front door.

Upon entering, Masaru and Mitsuki met a lovely receptionist. She showed them the list of 4 year old children that they have under their care.

But because the couple wanted to pick the right child to be part of their family, just looking at a list won’t help them alone, so they were shown inside.

Its play time for the children when the couple arrived, so all of them were either outside playing in the yard, or inside in the play area where some draw and read.

Among the children, some has already developed their quirks; obvious and unique, others not yet.

Even though the couple didn’t care if their new child will have a quirk or not cause they will love you the way you are, but if you were looking for a child in a place where there is a lot, then its pretty difficult to make a decision.

“There’s so many, how can we pick just one?” The brwon haired husband, Masaru asked Mitsuki, the blonde female who came up with the idea of adopting a child.

“I don’t know, but I know that I definitely want a girl.” She answered looking around.

“But what would Katsuki think about that?” Masaru worriedly asked nervous of the outcome but it fell through deaf ears as his wife excitedly look around.

“Oh no! Our ball!” A kid yell from outside catching their attention.

A group of children huddled around a tall twisty tree that has a bright red ball sitting on a high branch.

“Mo, you get it! You have a flying quirk!” One yelled to another.

“What!? But he has a jumping quirk!”

“How about you!? You can control wind!”

“Not yet!”

The children bickered on about who shall retrieve their ball located on the high branch of the twisty tree but with all the arguing its an unlikely result that it will end.

“Ah, you guys are such scaredy-cats!” A voice chirped from above them. Looking eyes were on you, a 4 year old child with (h/c) and bright (e/c). Already scaling up the twisty tree maneuvering through the branches and leaves, with ease you made your way to the branch where the ball sat.

“Wow! (Y/N) you are so cool!” One of the girls cheered from the ground.

In triumph you grinned and laughed heartily. “I climb this tree all the time! Getting up here is a piece of cake!” You yelled and kicked the ball off the branch and watch in landed safely on the ground. The group below cheered happily.

You were about to climb down when you have forgotten about the protective mother bird, who’s nest was near to where the ball was. Upon instinct the protective feathered creature shrieked and squawked angrily surprising you to let go of the branch and at that you fell and landed onto a nearby bush.

“(Y/N)! You okay!?” The group gasped in surprise and worry.

To their surprise you jumped back to your feet posing like a mighty hero. “I’m alright!” You told them grinning wildly “A little fall wont hurt me!”

Satisfied with your answer they continued playing and once they were away, the grin on your face immediately dropped as you hunched over your aching injury as you slowly limped your way to an empty picnic bench.

“Ow....” You whimpered resting your arms on the table and comfortably sat on the chair.

Suddenly a large hand rested itself on your aching shoulder that caused a sudden jolt to travel down your nervous system. “Aaah! Ouch! Ouch! Ouch!!” You shrieked making the voice behind you panic.

“Sorry! Sorry! I am so sorry, are you okay!?” Looking over your shoulder you came face to face with the two adults, Masaru and Mitsuki. From the looks of it, it seems that they had witnessed your little stunt.

With worry clouding her eyes Mitsuki sat next to you, her mother hen sense activating after being shut down for so long.

“That was a hard fall. ” she commented “Doesn’t your back hurt?”

You nodded but did so with a bright smile. “Yeah, but its only a little, don’t worry! Nana can just patch me up when break is over!”.

“You were very brave. You went to get that ball all by yourself in that really tall tree!” Masaru said taking a seat on the opposite side of you.

“Of course! Someone has to take care of the others when in need!” You told them and they smile in fondness. You have a fire your spirit just like their son but you were also kind, something that he lack and they grew on you just like that.

The couple spent the rest of the day with you and you alone, it was as if they were your own loving parents from the start. By the time it reached 4 o’clock in the afternoon, they went over to the receptionist.

“Do you want to give them a new name?” asked the receptionist.

The two looked at each other with a knowing smile. “No, just giving her our last name is fine.” Mitsuki answered. The receptionist nodded and typed away in their computer. Both Bakugo’s had a large grin on their faces as they stared at a silly picture of you which was in place as a profile pic.

“Aw... you’re going now?” you pouted not knowing the real reason why they requested to see you by the door other than saying goodbye. The caretakers and employees all had smiles on their faces in amusement and some already had tears in brimming in their eyes. They will miss you greatly but are happy to be able to see you off.

“Yes, we are going home.” Masaru said with a smile beside him, Mitsuki had to hold in her grin and tongue from ruining the surprise as it was going so well.

“You two are smiling...” You noticed “Is it because you enjoyed our time together!?” The thought of that made you grin in achievement as both chuckled softly watching you beam in pride.

“I also love our time together! I hope we could have more!” you giggled in excitement.

“We would love to make more too, in the morning, in the afternoon, in the evening, when we eat, when we sleep, when we go out and, when we see each other after returning from school or work.” Mitsuki said slowly watching you with love filled eyes.

You giggled at her odd statement not getting the real meaning to it. “Your saying that as if I’m living with you!” you joked.

But their smiling faces and warm beaming eyes made the thought of ’just kidding’ falter.

You are.”

That was the final evidence. Looking around you saw all the other employees have eyes filled with joyful tears and smile that was proud and happy. You turned to the couple you will now be calling ‘mom’ and ‘dad’ and with a confirming nod you broke into tears.

You were so happy you leaped into their arms and sobbed in happiness, loving the warmth of security they give as they held on tight.

Everyone said their farewells through tears, sobs and final words, telling them one day you will see them again somewhere in the near future.

And by the time you were in the car, everyone; including the children are outside waving goodbye.

The sun was starting to set down on the horizon and street lights and building lights are slowly radiate one by one preparing for the dark night.

“Oh yes, (Y/N), I almost forgot to warn you, you are also gonna an older brother too, right now he’s fourteen year old.” Said Mitsuki who sat on the passenger seat looking back at you over her shoulder, watching you bounce on your seat with excitement.

“Really!? Wow! I hope he’s different..." You trailed off at the end distantly looking out the window watching the passing cars.

Mitsuki, who probably was the only one who barely heard it, blinked in surprise and confusion but she decided to leave it be.

They now officially adopted you, but they have yet to learn how much pain you have actually been through.

Upon reaching to your now house you awed at the large modern house and continued to do so as you all walked to the door while being carried by Masaru. “Oh, The lights are on... Guess Katsuki is already here” Mitsuki spoke as you walked up to the front of the door.

“Now, I must warn you. Your brother... he...uh... has an explosion of... personality—and his own dictionary of words —but he is... kinda hard to warm up to.. so, don’t take his words to heart.” She warned and opened the door to an empty corridor.

“Ah, looks like he is upstairs... Hold on.” Mitsuki told them as she removed her shoes and walked up the stairs. The two of you also started removing your shoes. “Are you excited to meet your brother?” Asked Masaru.

“Yup! How bad can he be?!” you grinned.

So innocent... I kind feel sorry...′ Masaru thought as he nervously smiled and placed their shoes on the shoe rack.

Suddenly sounds of explosion and yelling was heard, some words even able to get through the floors and still be clear like water. “KATSUKI, COME DOWN YOU HAVE SOMEONE TO MEET!!”

“Th-This happens sometimes...” Masaru stuttered to you.


“Your foul mouth is on mouth arrest! Now go downstairs and meet (Y/N)!!”

“Who the fuck is that!?!”

“Language!!!” After that yell, a 14 year old boy with spiky blonde hair stumbled down the stairs and his sharp red orbs came in contact with (e/c) orbs that glowed innocently and curiously.

His eyes ressemble ones that belong to a wild animal, and his lips seem to form a permanent scowl, that didn’t seem to scare you, and his posture clearly showing no interest in you or the situation now, not that he properly know of it, that’s why his brows were scrunched together in confusion.

“Who the fuck is this extra and what are they doing here?” He rudely asked.

“Katsuki...” Mitsuki started slowly with a warning tone. “This is your new adopted sister, Bakugo (Y/N).” The room was dead silent as Katsuki slowly process what his mother told him glancing between you and his mother repeatedly before exclaiming in pure shock.


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