Natsuhara Yukihui (Matsumoto Wakana) has been the focus of everyone's attention in the class since junior high school. After graduation, she married and had children, and her happy life is a model. However, bad luck came to her without warning, and she and her family became victims of a bloody and brutal murder case. All signs show that the murderer was not seeking money, but more like a revenge. Tanaka Takeshi (Tsumabuki Satoshi) is a newspaper reporter who decided to dig out the truth behind the case. Takeshi has a sister named Mitsuko (Mitsushima Hikaru), who was imprisoned for abusing her biological daughter to death and was diagnosed with mental disorders. Takeshi visited Natsuhara's former alumni and friends, and her unknown dark history gradually surfaced, and this history was inextricably linked to Mitsuko.