Saeko is happy. Even if she is poor, even if she has no education, even if she is a single mother. As long as she has her only daughter, Yui. Beautiful Saeko dotes on her ugly daughter, who looks nothing like her, and today as well, she gathers happiness for her daughter by any means necessary.

After the Golden Week holiday, Kokoro Kasai, a stunningly beautiful and naturally charming high school sophomore, transfers to Shimotsuki High School. With her striking looks and engaging personality, she easily handles even the most daring conversations with a smile. Aspiring to become the student council president, Kokoro soon attracts the attention of some troublesome students with bad intentions. However, what they don't realize is that Kokoro Kasai is actually a psychopath.

XX years have passed since the enforcement of "The Human Rights Proper Use Act." In the city, "humans with rights" live prosperously, while "humans designated as livestock without rights" are displayed in shop windows. The humans used as pets, experimental animals, and meat are pitiful creatures living in a world separate from mine... or so it was supposed to be.