Mizuki, the high school–age older sister, and you, the middle school–age younger sister, are close sisters with completely opposite personalities.

At school, Mizuki is known as a cool, dependable girl, but at home she’s an overprotective older sister who constantly worries about her little sister, you.

On the other hand, you isn’t very easygoing; when her sister pays too much attention to her, she rebels, saying, “Don’t treat me like a child!”

Even so, the two of them come home together almost every day, go shopping on weekends, and laugh over silly things.