Since the Meiji Restoration, the penitentiary administrative system and design of penal buildings in Japan have been developed with reference to examples from Western countries as part of an institutional modernization effort. The policy has been to discipline prisoners based on benevolence and humanism, not to punish. It was around 1900 that a unified system of jurisdiction for all prisons was established in Japan by the Ministry of Justice. Since then, based on the humanitarian principles that had been set forth since the early Meiji era, the penitentiary buildings were upgraded under the organization of the Ministry of Justice, following administrative changes in the treatment and management of inmates. In 1922, “The Revised Penal Code” changed the word for ‘prison’ from "kangoku" to "keimusyo", with the clear purpose of moving from "retributionism", which punished criminals, to "educationism", which viewed prisons as institutions for the rehabilitation of prisoners. This paper considers the reform movement from around 1920, as well as structural restoration works undertaken in after the Great Kanto Earthquake (1923). This period represents an important turning point in the improvement of pre-World War II penitentiary buildings in Japan, demonstrating an identifiable new policy of penitentiary administration. This is reflected in the architectural planning of prisons, and expressed in designs utilizing the characteristics of reinforced concrete, a novel structural technology at the time.
The new policy can be seen in the planning of three architectural aspects: plot plans, office buildings, and cellblocks. Firstly, regarding plot plans, in the Meiji and Taisho periods, a large space was created between the front gate and the office, cellblocks (for ordinary prisoners) and the factory were combined into that space. Moreover, cells that should be segregated from ordinary prisoners (e.g. female, juvenile, and sick prisoners) were housed by demarcating the premises with walls. In contrast, in the early Showa era (around 1930), the premises were divided into a "government office area" and a "prison area", and the prison area was divided into a "cell house area" and a "factory area". This change was aimed at redefining the prison as the "government office" and reforming the image of executions.
Secondly, office buildings also reflected the new "governmental" nature of the prison. The features of the buildings include expanded functions aimed at improving staff well-being, rationalized operational flow planning, and brighter design of the facade and the interior.
Thirdly, in the early Showa era, each prison was divided into different types of confinement cellblocks in a more detailed manner, and the “radial”, “parallel”, or “composite” layout was selected according to the nature of the inmates. Large openings and top-lighting to ensure light and ventilation, and state-of-the-art sanitary facilities were also used to improve the living environment for the inmates.
The design of Kosuge Prison was one of the first to adopt the new execution policy at the time. Designed by Shigeo Kambara, an architectural engineer at the Ministry of Justice, it demonstrates the utmost importance placed on “purposefulness” in prison architecture as it responded to the changing needs of prisoners. By taking advantage of new structural technology, this ambitious new design strengthened the detention classification system, improved the living environment, and renewed the image of the prison.
