While participating in the discourse of world religions, Japanese biographers published accounts of Muhammad’s life in many genres of academic and popular books during the Meiji and Taisho eras (1868–1926). This article unravels how these biographical accounts played a crucial role in facilitating a geographical imaginary of Asia/the East that incorporated both Japan and West Asia. Situated in a radically different context from the Victorian biographers who inspired them, Japanese biographers constantly compared Muhammad to historical figures familiar to them, most notably Buddha and Nichiren, and reinterpreted the life of Muhammad while relying exclusively on European-language sources. In particular, in contrast to another strand of pan-Asianism that stressed peacefulness as an inherent quality of the East, the biographers identified Muhammad’s perceived militancy and the miracles he performed as signs of the shared values between Japan and Islamic civilization. Through the person of Muhammad as a concrete piece of evidence, Japanese biographers reimagined an Eastern civilizational space that could stretch from Tokyo to Mecca.