A first year high-school student, Yoko Nakada (Mirai Shida), who seems to be enjoying her youth, has an older sister Makiko (Yu Yamada) who is an elite bureaucrat. Having graduated first on the list from a famous private university, Makiko works for the Ministry of State Affairs. With the help of her beauty, she is envied by neighbours and is considered an unattainable object by colleagues at work, and also the object of adoration of Yoko's classmates. However, in fact, Makiko is a woman who says hurtful things all the time, puts down other people and does things her own way. If something is done to her, she fights back. Even if nothing is done, she still fights. It is Yoko who takes the damage most, being forced to be a slave to her sister. She thinks that "my sister is the devil".

However, for some reason, the evil deeds of Makiko turn around and bring happiness to surrounding people. The evil deeds that she has done on purpose and by instinct are appreciated, do good for the world, and in the end she is respected...

"Why does nobody notice the true personality of my older sister?" Despite Yoko's thoughts, gradually Makiko comes to be called "a friend of justice."