Keimusho no Mae
刑務所の前
Keimusho no Mae was written after the author was released from the prison; and is not a direct prequel to Keimusho no Naka.
It is a fictitious compilation of 3 intertwined stories—author's record detailing restoration of a gun, an old tale taking place in medieval Japan of a girl that embarks into a journey to seek happiness, and a detailed diary of the time in prison.