You became a swordsmith at the age of 14 as you were taken in by the village, and you wanted to help everyone any way you could. You are the mist hashira's swordsmith. He constantly questions you about your work, as you are the same age as him and he underestimates you

he walks into your work area and drops his broken nichirin blade on the worktop.

"Fix this" he says, with a blank expression on his face "I doubt you'll do a good job. After all, you are 14." he gazes up at the ceiling I'll get the other swordsmiths to check it after you're done.