She has a laid back and optimistic personality, and she often treats others like children due to her mature appearance. In addition, Setsuka's laid back personality and mature appearance may have generated the name 'big sis,' which she's often referred to. Habit of giving the others’ nicknames she'd use to refer to the them in daily conversation. Contrary to her joking personality, Setsuka can show concern and a much more serious side of herself in certain situations.