Katsuki Bakugou x little sister (OC)

Hairdressers

Knock knock

That was the door and in came Midoriya and Mirio.

"Deku-kun!" Eri said waving at Izuku.

"Deku? Why are you calling Izu-Chan Deku?" Masumi asked seriously.

"Oh no Sumi I-it's c-cause." 

"Are you bullying izu-Chan??" 

"Only my nii-Chan calls him dat but nii-Chan is very silly!"Masumi pouted

"I can't be friends with a BULLY!" Masumi said, "even if she is a Princess." She whispered the last bit.

"Oh Deku is Midoriya's hero name!" Mirio said proudly.

"Really? But why?" Masumi asked confused looking up at Deku and Mirio.

"Because I changed the meaning of Deku to me......to me it means 'you can do it'" Deku said inspirationally.

"Wooooooooowww Izu-Chan is so cool!" Masumi looked at Izuku in awe, stars in her eyes.

"Urmm y-yea t-thank you!" Izuku stuttered backing away slightly.

"Sorry Eri-Chan I didn't know!" Masumi said bending down in apology at, at least a 90 degree angle.

"Aha! It's ok!" Eri said waving her hands frantically.

"Sumi your brother said  I should pick you up so urm!" Deku mumbled.

"Let's bring Eri!" Masumi shouted grabbing Eri's hand and pulling her closer to her.

"How about you ask her before dragging her along with you." Mirio asked bending down to Masumi's level.

"Oh I didn't know.." Masumi said lowering her head.

"I want to go with Mi-Chan please!" Eri said happily squeezing Masumi's hand.

"You do?" Masumi asked raising her head up and Eri nodded vigorously.

"Ok den let's go!" Masumi reached for Deku's hand and held it.

"So cute omg she has such small little hands awww how does Katsuki have such an adorable sister their personality's contrast so differently, how did she perform such a large explosion with such soft delicate hands maybe her quirk makes her immune to it....." Izuku mumbled.

"IZU-CHAN YOU ARE MUMBLING AGAIN!" Masumi shouted.

"Oh urmm sorry right then let's go." Izuku said followed by the little train behind him of linked hands.

Timeskip

"The dorms are SOOOO big!" Masumi hesitated before following Deku inside.

"Come on Mi-Chan!" Eri smiled at Masumi.

"Kk!" 

"Nii-chan hiiiii!" Masumi spotted her brother standing next to Kirishima and ran to him but as she got close Katsuki quickly moved out of the way and she landed on the floor.

"Onii-chan why are you so meaaaannn!" Masumi mumbled into the floor.

"Aha! Masumi are you alright!" Deku said running up to the fallen girl but before he reached her she sprung back up.

"I'm fine!"

"Are you sure?" Deku said checking her head and arms for any cuts.

"Yes I'm surer then sure!" Masumi smiled but then her smile faltered

"What happened!" Deku asked he could feel an intense aura behind him so he turned around.

"So you think you are better brother than me HUH DEKU!" Bakugou said angrily towering over Deku.