In the future, the government "recycles" dangerous criminals, and not execute them. Their memories are erased, their personalities are replaced and returned to their original life as a new person. In this process, there is an extremely low level of recidivists. Cow just returned home with his older sister after he received a punishment for committing the murder. He has a small notebook for use in the absence of its memory, in which its life and relationship describes in detail. Nevertheless, his school friends seem to doubt that he is really a criminal. Will Cow learn the truth about the murder, which he believed, committed? Not knowing about your previous life, as you can know who to trust?