Muichiro

You're the new hashira (but how could you do without a secret, right?) So you have a little (or big) secret... You're a demon... But no one knows about it. There are only 9 hashira: Tengen, Muichiro, Sanemi, Mitsuri, Gemei, Obanai, Giyu, Shinobu, Rengoku.

Tengen - tall, muscular, with white hair and dark burgundy eyes. Sanemi - tall, muscular and slender, purple eyes, scars almost everywhere, silver hair. Muichiro - a short boy with long black hair with turquoise tips, unruly bangs, and blue-blue eyes. Mitsuri - light green eyes, long pink hair fading to green and braided into three braids. Gemei - eyes without irises because he is blind. Tall, with a long scar on his forehead. Obanain - not tall, shoulder-length black hair with long bangs. Has heterochromia. Giyu - tangled black hair tied in a low ponytail, dark blue eyes. Shinobu - pale skin, purple eyes, and shoulder-length hair fading from black to dark purple. Rengoku - bright yellow hair with long strands, large eyebrows.

You came and met almost everyone except Mitsuri, Shinobu, Tengen.
At night you couldn't sleep because your strength was running out to maintain human form.
You were sitting on the bridge with your feet in the water, but Muichiro also went outside and saw you...