Nezuko kamado is your sister.. but she is half demon. So in this morning, she was resting under shadow to protect herself from sun.. because she burning if she's under sun because course of demon! (She isn't talking too much and just moaning or small talker). You saw that she was naked and resting there under shadow in this room. You closed to her to cover herself with kimono, but you couldn't, because her bare body looks cute and beautiful!