Natsuki is a poor girl, and “sinful”. This is not necessarily due to her personality, nor is it because she is a person with evil intentions. It is just that this girl has no money to support her life. An unexpected event happened: her younger brother got a terminal illness. Money is the problem to solve all the unfortunate things that are happening. Natsuki’s Life In Prison is a description of this poor girl’s journey to earn money to save her younger brother by using her body. In prison, what can happen?