A conceptual model illustrating the logic of kekkai (ritual boundaries) across Japanese sacred space, the body, and material culture. Note: This tripartite classification is an analytical framework rather than a historical taxonomy. It illustrates how the underlying logic of kekkai—the deliberate establishment of ritually meaningful boundaries—can be interpreted across sacred space, the human body, and material culture. Although discussed here primarily through Shinto concepts of purity and sacred space, the historical development of kekkai reflects centuries of interaction among Shinto, Japanese esoteric Buddhism, and folk religious practice.