This paper explores the scholarly discourse on the divinity of the emperor in postwar Japan to better understand Japanese conservative nationalism, which has been regaining momentum since the 1990s. Viewing the idea of the divinity of the emperor as ideologically fundamental to Japanese conservative nationalism, this paper looks at how conservative scholars from the 1970s developed a culturalist argument for the divinity of the emperor, first to negate the “humanity declaration”, i.e., the New Year’s greeting by the Showa emperor on 1 January 1946 renouncing his divinity, and then to reconfigure conservative ideology into a popular discourse on Japanese identity (i.e., the Nihonjin-ron), thereby making it more easily accepted by postwar society. Key to this culturalist argument is an essentialized dichotomy between Japanese culture and Western culture, more specifically a binary between Shinto kami and the Christian God—that the Japanese concept of kami is qualitatively different from that of the Christian God, so the emperor is not God but is kami; therefore, the emperor’s divinity is not really denied and he remains the spiritual pillar of the Japanese nation even under the postwar constitutional regime. Refashioning itself as part of the increasingly popular but depoliticized Nihonjin-ron discourse, the culturalist argument on the divinity of the emperor helped make the imperial house a popular topic of the discourse on Japanese identities, even while it completely circumvented the very issues of war responsibility and historical memory which gave rise to the “humanity declaration” in 1946 in the first place. In its depoliticized, popularly appealing form, the culturalist argument played a role in legitimating the regressive conservative nationalism that seeks to revive the pre-1945 divine emperor-centered political regime. Exploring the scholarly discourse on the divinity of the emperor, then, helps shed light on how and why conservative nationalism could persist and gain momentum in the 21st century.