Traditional Japanese architecture is known for its open, ambiguous spatial boundaries (“kyokai”), which integrate nature and dwelling through Zen/Shinto philosophies. Yet modern urban housing, driven by high-density minimalism, flattens spatial hierarchies and erodes these rich boundary concepts. This study aims to explore how Japanese architect Yoshiji Takehara reinterprets traditional spatial principles to reconstruct the interior–exterior relationships in modern housing through a mixed-methods approach—including a literature review, case studies, and semi-structured interviews—verifying the hypothesis that he achieves the modern translation of traditional “kyokai” through strategies of boundary expansion and ambiguity. Analyzing 78 independent residential projects by Takehara and incorporating his interview texts, the research employs spatial typology and statistical methods to quantify the characteristics of boundary configurations, such as building contour morphology, opening orientations, and transitional space types, to reveal the internal logic of his design strategies. This study identifies two core strategies through which Takehara redefines spatial boundaries: firstly, clustered building layouts, multi-directional openings, and visual connections between courtyards and private functional spaces extend interface areas, enhancing interactions between nature and daily life; secondly, in-between spaces like corridors and doma (earthen-floored transitional zones), double-layered fixtures, and floor-level variations blur physical and psychological boundaries, creating multilayered permeability. Case studies demonstrate that his designs not only inherit traditional elements such as indented plans and semi-outdoor buffers but also revitalize the essence of “dwelling” through contemporary expressions, achieving dynamic visual experiences and poetic inhabitation within limited sites via complex boundary configurations and fluid thresholds. This research provides reusable boundary design strategies for high-density urban housing, such as multi-directional openings and buffer space typologies, and fills a research gap in the systematic translation of traditional “kyokai” theory into modern architecture, offering new insights for reconstructing the natural connection in residential spaces.

This study explores the design characteristics of approach spaces in architect Yoshiji Takehara’s independent residential works, focusing on their spatial arrangement, sinuosity, and experiential qualities. Through the analysis of Takehara’s projects and interviews with the architect, the research identifies key patterns in approach configurations, including entrance positioning, path complexity, and site-specific adaptations. The findings reveal that Takehara’s designs emphasize winding paths and deliberate spatial sequences, contrasting the simpler approaches of contemporaneous residential designs. The study categorizes approach configurations into distinct typologies, influenced by the site dimensions and entrance placement, and highlights a shift from physical obstructions to subtler, psychologically guided design elements over time. Takehara’s design method translates the concept of “Ma” from traditional tea gardens into the language of modern pathways, integrating traditional Japanese spatial ambiguity into contemporary residential design. This offers strategies to enhance spatial perception and experiential richness. Particularly in compact urban settings, the research provides valuable insights for contemporary residential design, emphasizing the importance of landscape-oriented approaches and spatial sequencing in creating meaningful entry experiences.

Residential courtyards serve as critical mediators between architecture and nature in contemporary high-density urban environments. However, extant scholarship predominantly examines isolated courtyard typologies, lacking comprehensive systemic analysis, while contemporary designs frequently suffer from functional diminishment. This study investigates 72 representative Japanese detached residential projects (2015–2024) to systematically analyze spatial configurations, compositional characteristics, and functional interrelationships between courtyards and interior spaces. The methodological framework incorporates typological classification based on spatial positioning and constituent elements, coupled with analytical examination of aperture connections, interpreted through the lens of pattern language theory. Findings reveal a distinct hierarchical organization and a set of recurrent design patterns: front courtyards predominantly employ “partially walkable” surfaces with symbol trees to reconcile circulatory and esthetic functions, establishing a transitional sequence; central courtyards achieve daylight optimization and spatial extension through compact dimensions and non-paved surfaces, creating intimate outdoor rooms; side courtyards demonstrate scale-dependent adaptive strategies for privacy and microclimate regulation. The predominant living room-courtyard interface configuration features “group-planted trees with large openings,” creating vertically stratified visual experiences. This tripartite system translates traditional nature concepts into evidence-based spatial patterns, providing a transferable design matrix and pattern language for human-centered courtyard design in high-density contexts.

The relationship between architecture and sloping terrain constitutes a persistent subject in architectural discourse. Western scholarship has often emphasized structural, technical, and formal strategies, whereas systematic sectional studies focusing on Japanese residential works in sloped environments remain comparatively underexplored. This study aims to elucidate the characteristics and design logic of sectional composition through an analysis of 55 independent Japanese residential projects on sloping terrain from the period 2015 to 2024. Employing an analytical framework that integrates external composition (orientation of the approach path and grounding condition of the building volume) with internal composition (sectional relationship between the entrance and the main room), the research identifies six fundamental sectional types and their sub-patterns. From these, three core design logics are derived: transforming slope directionality into internal circulation sequences, establishing a contrastive relationship between building volume and terrain, and adapting the terrain through leveling to prioritize functional layout. By maintaining a consistent analytical framework with the foundational study, the research enables a diachronic comparison that reveals both continuities and shifts in sectional design strategies over the past two decades. Architects’ own design statements are incorporated to corroborate the spatial narratives embedded in these compositional strategies. The findings demonstrate that contemporary Japanese sloping terrain residences employ diverse approaches ranging from topographic integration to volumetric dialog, showing that sectional organization not only responds to topographic conditions but also shapes spatial experience and dwelling logic. This study provides a typological reference for sloping terrain residential design and contributes an empirical foundation for understanding the intrinsic compositional relationship between architecture and terrain.