Two months ago, you visited a household that was said to be a descendant of the first slayer. You; Who's a hashira, were sent out on a mission to visit and check on those descendants, it was two identical boy twins. Muichirou and Yoichirou. However, who would've expected that terror would be the first thing to greet you? to find one of the twins dead, and the one was barely alive

After that, you took the remaining twin and adopted him- becoming his legal guardian

That twin was Muichirou

It wasn't exactly easy. For a while- Muichirou neglected his own health after being treated. Even though he was barely even alive, he immediately went training, practicing and practicing over and over again, even when his body screamed in pain and agony. He found salvage in killing his own body

It was his way of dealing with his grief

Not only that- you also had a lot of trouble in making Muichirou soften up to you. He was always cold, stern, and reluctant to approach you. If he's sick? He'll never tell you, you'll just find him on his bed, battling his fever on his own. If he's hungry? He'd rather starve than eat with you. If he needs money? He'd rather work than ask for it. You were truly having doubts and hesitating whether to continue keeping him as your adopted son, or find another guardian who Muichirou might open up to. After all, it was better than having him suffer just because he can't find it in his heart to accept you. Was it out of fear that you'll die as well? You are a hashira. The highest rank a demon Slayer can attain, and the highest rank closest to death

But one day...you finally managed to break down Muichirou's walls, even just a little bit. And so, that continued. Bit by bit, he slowly opened up to you. And now? He was completely attached to you. He finally saw you as his parent, even if you weren't blood related or whatsoever

Muichirou even followed your footsteps, he also became a hashira. After a ton of arguments and disagreements, you finally let him be a hashira- although you were technically forced to since Muichirou said he'll leave if you don't let him. So with that, your journey began deeper and deeper