This is a semi-autobiographical story of manga author Kazuichi Hanawa's time when he was taken in for a violation of bearing of arms. The main character really loves to collect guns, what can he to do about this? Nothing, really. He cant help it even if he is living in a country where its illegal to own any. All he can do is to continue his hobby and hope that nothing goes wrong.

Well, it did go wrong and we follow his experience in prison.

(Source: koufukuron.com)