["Journal for the Scientific Study of Religion, EarlyView. ", "\nABSTRACT\nThis research note analyzes the ambiguous boundaries of religious identity, belief, and ritual behavior in Japan, drawing on data from a nationally representative postal survey conducted in 2024 (N = 3947). The findings reveal widespread participation in Buddhist and Shinto rituals even among individuals who identify as nonreligious or atheist, as well as the prevalence of overlapping religious affiliations. Beliefs in gods and the afterlife also vary widely and do not align neatly with religious identity categories. These results highlight how religiosity in Japan is often expressed through culturally embedded practices and inherited traditions, rather than formal belief or institutional membership. A comparative review of other national surveys shows that minor changes in question wording can significantly affect reported religiosity. By documenting the plural and diffuse nature of Japanese religiosity, this study contributes to a more nuanced understanding of religion in East Asia and offers methodological insights for future cross‐cultural surveys.\n"]