Author: In this AU, Y/n's father took the trio (Aizawa, Mic, and Shirakumo) for their work study, so Shirakumo didn't die cause F/n protected them.
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It was a normal day at the Butterfly Mansion. Y/n has just finished taking entrance exam at UA with Midoriya. For now, he's waiting for the result of the exam.
M/n was cooking for their dinner while F/n, on his day off, he was watching news at the tv. Y/n's father has made a huge leap on hero ranking, he's a number 7 hero and had his own agency.
"So, our son is attending UA?" F/n asked.
M/n hummed in respond without glancing at him. "The result should be arriving anytime soon. Anyways, dinner is ready."
After placing the last plate, M/n glances at her son's room.
"Y/n! Dinner's ready! Both you and your father's favourite!"
The mini Tomioka immediately rushes out of his room, towards the table. Both of the adults chuckled at their child.
F/n ruffled his son's hair before he sat down. The three of them start to have their dinner.
A few minutes later, Kanzaburo flew towards them, with a letter.
"Little giyuu... It's from UA..."
F/n took the letter from Kanzaburo and caressed him.
"Are you ready to see the result?" F/n asked Y/n who appears to be nervous.
"Yeah. I'm ready." Y/n nodded before taking the letter and opened it.
A small device fell and a hologram of All Might appeared. Stating about Y/n's performance and his high score.
"Congratulation Young Tomioka and welcome to you hero academia!"
Y/n turn to his parents who was smiling and proud at him. M/n was the first to approach him and pulls him into an embrace.
"I'm so happy for you Y/n. You're gonna be a fine hero that you wanted to be." M/n murmured softly.
"I'm very proud of you, son." F/n ruffled Y/n's hair again and proudly smile at him.
"Mom. Dad. I'll do my best to become strong, so that I could protect you."
The next day, Y/n was preparing to depart from their mansion. Taking the bento his mother made for him.
"I'll be heading out! Mom! Dad!"
"Alright! Goodluck on your first day!" M/n replied. While F/n was fixing on his hero costume.
But before Y/n could leave, he look back at his parents.
"Oh I forgot. Mom, are you feeling okay now?" Y/n asked. M/n raised an brow at Y/n before he continue. "Last night, I heard you were screaming Dad's name. I was assuming that you probably had a nightmare about Dad. But if everything's alright now, that reliefs me. See you later."
With that, Y/n finally left the mansion, leaving M/n who had redden face while F/n was frozen in place.
"I didn't know he's still awake last night. But don't worry, he thought you just had a nightmare. Our boy has an innocent mind."
"You're not having Salmon Daikon for a year and he better stay innocent."
"Eh-"
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After the first day of UA, Aizawa spotted Y/n and his classmates heading towards the gates. To him, Y/n seems very familiar and his swordsmanship.
His eyes caught a familiar figure that has a kitsune mask, standing at the gates and being swarmed by students.
"No way! Number 7 hero Water Samurai: Mizuchi!"
"So cool!"
"What is he doing here?"
Aizawa blinked and shockingly at the hero he internship with.
"Pardon me fellas. I'm only here to pick my son who was also his first day here." F/n said in a kind tone to the students.
"Tomioka! I didn't know your father is the number 7!" Iida said.
"Yeah! It's so cool!" Uraraka added. "Have you known this Deku-kun?"
"Yeah. Mr. Tomioka known me since I became friends with Y/n. Also I've never seen your dad taking off his mask." Midoriya said.
Y/n sighed. "I'm only saying this to you guys. My father and I have same appearance, but his hair is short." The trio ohh'd and nodded.
"Ah! There you are Y/n!" F/n calls out to Y/n, waving at him.
Y/n say his farewell at his classmates and approach his father who asked him how his first day.
"So, how's your first day?" F/n asked, wearing the kitsune mask.
"It was good. We had an Quirk assessment test but I managed to got first place with the techniques." Y/n replied.
"Oh? That's amazing!" F/n said as he messily ruffled the boy's hair. Y/n frowned by it. "So, who's your teacher?"
"The Erasure Hero: Eraserhead. He's our homeroom teacher."
"Aizawa-kun? Really?"
"Eh? You know Aizawa-sensei?"
"Him and his two friends work study with me during their youth days." F/n answered before they both left to head back to their butterfly mansion.
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Villains attack the USJ. Aizawa fought the villains alone while Thirteen attempts to evacuate the students.
There are two nomus beside Shigaraki, one of them had a warping Quirk.
Meanwhile at F/n's agency, one of F/n's sidekick rush to his office.
"Mizuchi-san! We just got a report that USJ were under attack by villains! There are only two UA teachers there defending their students!"
"Understood." F/n puts his kitsune mask on and grabbed his katana. "I'll go there."
Back at the USJ, Y/n look in horror when he saw his teacher gets brutally beat up by the Nomu.
His body moved and rushes in to save his teacher.
"Water Breathing, Sixth Form: Whirlpool!!"
Y/n engaged battle with the Nomu. Aizawa weakly look at them.
"T-Tomioka! Get away from here!"
Y/n didn't listen to him as he continue to fight the Nomu, to Aizawa's surprise, Y/n is keeping up with the Nomu's speed and strength.
"That's good. Keep it up and you're heading towards to your death." Shigaraki sneaks behind Y/n.
The boy's eyes widened as Shigaraki's hand slowly reaches to him and the Nomu is about to crush him.
'Crap!'
"Y/n!" Midoriya dash towards him.
Suddenly, F/n appeared by bursting in from the roof. He spotted the familiar mismatched haori, being cornered by villains.
"Whoa! Is that number 7, Water Samurai: Mizuchi!" Kirishima exclaimed as the rest was relief to see a pro hero arrived.
"..D-Dad!"
"Oh? Is that your daddy? That's cool." Shigaraki said.
"Hey you. Step away from my son."
The masked kitsune quickly dashed towards them, grabbing Y/n and Midoriya, and distance themselves from the villains.
The Nomu suddenly had a deep cut on its chest and one of Shigaraki's hands were sliced in half, causing him to panic and enraged.
"That was fast.. Dad?"
"Mr. Tomioka!"
"Everything's alright now." F/n said.
The USJ entrance suddenly burst open and All Might walks in furiously. He dash towards the wounded Aizawa while beating the villains on his way.
"Aizawa-kun.." F/n uttered in concern.
"It's alright Mizuchi. He's just unconscious." All Might said as he approaches them.
He told the students to look after their teacher before the two top pro heroes faces Shigaraki and two Nomus.
"Aizawa-sensei, just hang in there." Y/n said.
Aizawa slowly regain his consciousness and avert his eyes towards the fight.
"Both All Might and Mizuchi are amazing! They can defeat them!" Midoriya said.
"Yeah." Y/n said. He watch his father easily defeated the other Nomu using the Breath of Water.
His father was Quirkless, but he fully master the Breath of Water swordsmanship. Making him like he deserve a Water Hashira position.
Afterwards, Mic and Shirakumo visited their friend.
"Hey Shouta! Don't you dare lose! This isn't how your gonna die!" Shirakumo said.
"Yeaah! We got a lot things to do in the future!" Mic added.
"Will you two be quiet?"
"Oh my. It seems like I was worrying nothing." The trio turn around and saw their former mentor with his wife.
"Mr. And Mrs. Tomioka!" Shirakumo and Mic both said before they greeted them.
"How are you feeling Aizawa-kun?" M/n asked as they walk in.
"I'm fine."
"I'm glad. You did an amazing job protecting your students." M/n smiled and lift a basket of fruits. "Here. These are for you and Thirteen."
"I'll take that ma'am." Shirakumo took the basket.
Y/n take a quick look from the doorway, surprised to see his parents knew his teachers. "I never knew this. Even Cloud-sensei is here-"
"I knew that little Tomioka is familiar! He's grown up!" Shirakumo said before he noticed Y/n. "There you are!"
"Gah!" Y/n begins to run away as Shirakumo followed him.
"Hey! Don't you run away from uncle Shirakumo! I was your favourite when you were little!"
"I don't remember that!!!"
---
At the Sports festival, F/n exchange dirty look with the Flame hero: Endeavor when Todoroki and Y/n's is about to start.
"Shotooo!!! You not hesitate to use your flames! With my blood, you will surpass me!"
Todoroki frowned and ignored his father.
"Y/n!"
Y/n and some of the audience look towards F/n, as he remove his mask.
"Show them and prove that you are a descendant of the Water Hashira."
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Author: Anyone wants a part 2 of this?