This dissertation examines the history of the Japanese community in Shanghai between 1895 and 1937. Situated at the intersection of the study of Japan’s empire and overseas expansion, imperialism in China, the urban history of treaty ports, and the study of modern Shanghai, this project offers a fresh perspective on Japan’s ascent as a colonial power and its impact on the established imperial order in East Asia. It moves beyond the simplistic portrayal of Japan as a late entrant into China’s treaty-port system with an aim to subvert the “semi-colonial” or “transnational colonial” structures dominated by Western powers—a narrative that risks reading history backwards from Japan’s full-scale war efforts after 1937. Instead, it explores how the Japanese integrated themselves into the treaty-port configuration while reappropriating its existing institutions. Throughout the early twentieth century, Japanese presence in Shanghai and the city’s evolvement as a modern cosmopolis profoundly influenced each other. Specifically, this study investigates the interlinkage of the Japanese challenge to British control over municipal governance, their response to the rise of Chinese nationalism, and their quotidian experience that was constantly shaped by the built environment of the host city. Central to my analysis is how ordinary Japanese settlers negotiated their position in Shanghai’s International Settlement, and how their contestation of the treaty port’s entrenched political and racial hierarchy eventually led to a stronger alignment with their state power, which ultimately compromised the Settlement’s tradition of self-governance and inter-imperial cooperation. This project employs a synthetic analysis that weaves together local, national and transnational perspectives to illuminate key aspects of East Asia’s modern transformation, including the conceptualization and practice of imperial dominance, nationalist resistance, community-building, state-society relations, and the development of urban administration, showing how these dynamics interacted with each other in shaping the political, social, and spatial fabric of treaty-port colonialism. To this end, it draws upon a diverse array of sources in multiple languages, including documents from the Shanghai Municipal Archives, the National Archives of Japan, and the archives of the British Foreign Office and the U.S. Department of State; it also combines a broad selection of newspapers and periodicals from both Shanghai and the imperial metropoles, as well as guidebooks, local gazetteers, police records, personal writings and memoirs, to provide a multifaceted and balanced view essential to understanding Japanese interaction with the treaty-port regime.