If Deku Was Part Demon (Demon Slayers x MHA/BNHA)

Chapter 7: The Mission & Muzan's Past

[A/N: I do not own this video rights go to the creator(s). I also don't own KNY or the characters from MHA or Other anime. I only own this fanfic and my OC Amber. Thank you all for your support for this story. Now without any further ado let's continue the story.]

Izuku's POV

"Caw! caw! There's a demon kidnapping girls in the dead of night and they never return. Caw! Caw! Your first mission is to kill this demon and stop it from killing anyone else! Caw! Caw! Do you accept the mission?" Tuie my crow said, I grinned.

"Of course I accept. Who do you take me for Tuie, a coward, also can I have Tanjiro, Amber, and Nezuko come with me?" I asked,

"Caw! Caw! Tanjiro, Amber, and Nezuko have been sent the same mission. Caw!" Tuie said, I threw up a piece of bread. He snatched it out of the air and ate it.

~Time-Skip~

We arrived around 4 in the afternoon. I smelled the air and immediately could tell not just one demon was here, but 2, and both are different.

"Tanjiro, Amber, Nezuko I'm going to go check something out while you three ask around about the missing girls. I'll be back soon." I said, as I was about to leave Amber grab my wrist.

"We need a way to know if it's you or not." She said,

"Oh right there are some demons that can transform into others. Amber your blood art allows you to keep track of those you have bitten, right?" I asked, she nodded.

I sighed and held out my arm. I flinched when she bit into my arm. She then released my arm and licked the wound clean. She then kissed me on the cheek.

"Try not to get too hurt." She said, as she went back to her siblings. I sighed.

"No promises." I said, before I disappeared and started following the demons scent.

The scent lead me to a bamboo forest, I soon see a trail and decided to follow it. The scent lead through the trail.

'Good, I'm heading the right way. The Demon's scent is getting stronger so I'm getting closer.' I thought, I continued walking up the trail until I came across a medium sized storage house.

I heard movement inside. I placed my hand on my katana, just in case they were to jump out and attack me. I then slowly and silently began moving forward. I immediately stopped when I picked up the sounds of light sobbing.

'Don't tell me...' I remember something Dad had told me when I was little.

~Flashback~

3rd Person's POV

"Dad how did you become a demon?" Izuku asked, he was there helping his adopted father Muzan in his lab.

Muzan froze for a moment before he decided to answer his adopted son.

"I was born as one, at that time demons being born was normal, but some humans didn't like it and most humans were afraid of us. So instead of trying to understand us. The humans did what they always do to things they were afraid of." Muzan said, Izuku tilted his head cutely.