This study revealed the process of urban transformation from the perspective of land ownership transition from 1888 to 2020, focusing on the historic city center of Kuroishi City. The process of decline in the city center began with a decrease in population from the 1950s, followed by an increase in absentee landlords from the 1960s, stagnation in land transactions from the 1970s, and a visible decline in commercial functions such as the number of stores and sales from the early 1980s onwards. Additionally, it was revealed that most absentee landlords reside within the city or nearby areas.

 In the erstwhile merchant town of Kuroishi City, a small city in a snowy region of Aomori Prefecture, “Komise,” a sheltered walkway in front of the townhouse, has created a safe space for people to walk on the street since the Edo period. Similarly, “Kaguji,” the open space behind the townhouse, has secured a space for snow accumulation in the inner part of the city block. Incidentally, “Komise” and “Kaguji,” at the front and back of the townhouse, respectively, have supported life in this heavy snowfall area.

 The Nakamachi area, with its traditional “Komise,” was selected as an Important Preservation District for Groups of Traditional Buildings in 2005. Efforts have been ongoing in this area to conserve the “Komise” streets since 1985. Additionally, the hitherto unused “Kaguji” has now been utilized to create a public space in the inside of a city block.

 The paper reveals the interconnection of “Komise” conservation and the maintenance of public space through “Kaguji” use, as well as the phased reorganization of the city block. These phases are summarized as follows:

 1. In the discussion between the government and the residents of Kuroishi City after 1985, the notability and importance of the function of the snow-proof passageway of “Komise” and the awareness of its ownership were clearly stated. It was positioned as a historical space at the heart of the urban renewal project for the revitalization of the shopping street and became a subject of conservation. Conversely, “Kaguji” was positioned as a residual space in the city block to complement street maintenance.

 2. Urban development since the 1990s has progressed in stages, with a series of small-scale spatial developments. The revitalization of “Komise,” the development of public spaces using “Kaguji,” and the development of circulation pathways have been interlocked, leading to the creation of a circulation environment not only at the front of the block but also in its inner part. Hereon, past methods will be used as a model for the reorganization of the surrounding blocks.

 3. The historicity of “Kaguji,” shared by neighboring houses, was recognized by the results of public space development, which allowed recent administrative plans to position it as a historical space to be inherited. After 30 years of effort, a perspective of the entire city block as a historical environment was formed.

 In conclusion, the case of the former merchant town of Kuroishi showed the possibility of a phased reorganization of the town area, where vacant land in the inner part of the city block is utilized to improve public space while conserving the townscape on the front side.