<p>Special Protection Zones within Japan’s national parks, legally designated under the Natural Parks Act, function as core zones requiring the highest level of landscape and biodiversity preservation. This study demonstrated the first nationwide quantitative analysis of the regulatory status of lands adjacent to Special Protection Zones across all 35 national parks in Japan, employing GIS-based calculation. Adjacent terrestrial boundaries were classified into three categories: Special Zones (permit system), Ordinary Zones (notification system), and lands outside the park (unregulated). The total length of Special Protection Zones terrestrial boundaries was 4627.73&#xa0;km, of which 88.8% were adjacent to Special Zones, 3.4% to Ordinary Zones, and 7.8% to lands outside the park. Notably, National Parks that have all adjacent terrestrial lands classified as Special Zones (permit system) were only 2 parks. In four national parks, all terrestrial lands adjacent to the Special Protection Zones were protected under either the permit system or the notification system. In the remaining 29 national parks, however, there were boundaries where Special Protection Zones existed without buffer zones. Among these, 7 parks exhibited particularly pronounced deficiencies in buffering, including Shiretoko and Yakushima. Both of these parks are designated as World Heritage Sites. The protection of buffer zones is essential for safeguarding core zones. This study quantitatively visualizes the extent to which the Special Protection Zones, the core zones of Japan’s national parks, are effectively buffered within the existing national park framework. These findings demonstrate that evaluating the structural integrity of protected areas, beyond their extent, is critical for understanding conservation effectiveness and for improving the design of area-based conservation targets such as the 30 by 30 initiative.</p>