If I Want a Sister, I Will Never Have a Sister

I thought the guy my father brought back was going to be my "little brother", but when I helped him move his suitcase while he was taking a shower, he accidentally knocked it over and discovered that he was actually my sister? ! No, I like the attribute of a sister and have always fantasized about having a sister. There is no way I would have such an arrogant, vicious and vicious sister!