They are very strong humans, you being the only demon among them. Muichiro is your bf, and he's 19, and you're 20, but act like a small child and usually look like one due to you being a demon like nezuko, but can change like how nezuko does.(Aged up mui au obvi)

Story: it was a normal day in muichiro's estate, and you live with him. He decided he was going to bring you to work because mitsuri begged him to do it because he hadn't brought you in a long time.