Otobe Shizuka is the only child of the Otobe family's previous kumichou. Succeeding her late parent, she becomes the kumichou of the family. The family's direction changed drastically during her predecessor's time, running a utility business in the local area, Shizuka inherits this work and has fostered good relationship with the local residents. Although it is undeniable that her presence​ at the school is a bit flamboyant, she does have a few close companions.

Always by her side as an escort, and also her childhood friend, Natatsuka Touko. The daughter of a renowned magician, despite being her kouhai, she adores her as a magic teacher, Kannagi Kino. Even though she is a kumichou, she still gets treated kindly by a senpai, Takanezawa Honami. And, from the ally Yakumo family, the granddaughter of its kumichou who currently works nearby as a nurse, Yakumo Rio.

Surrounded by such friends, Shizuka leads a peaceful school life, but that peace gradually begins to fade. In the area where she and the others live, for a while, there has been a talk about opening a casino, and there is a rumor that people from the underworld are influencing the discussion between those who oppose and those who support. Admiring the dealers whom she had seen in movies when she was young, Shizuka does not have a bad impression of the casino, but after learning that the lands are being flipped forcefully with the premise of opening a casino, she can no longer remains idle.

To encourage a honest and fair discussion, under her family name, she acts as a mediator, however, her naivety gets swallowed up by the malice of the adults. Shizuka, who places an unreasonable bet reluctantly and loses, in exchange for the peace for the residents, offers her own body. While trying her best to endure, her days of being toyed with by the merciless men continue. However, the malice of men encroaches Shizuka's friends as well.......