The latter period of Japanese colonial rule has long been considered a "dark age" in the history of Taiwanese theater, when the colonial government cut off Taiwanese theatrical traditions abruptly, and dominated the whole theatrical development with its radical assimilation policy called Kominka. This article reexamines the theatrical activities under the Kominka Movement in its first four years, and focuses its discussion on the following aspects: 1. the formation, transformation and execution of theater policies by the colonial government; 2. the rises and falls among different theater genres during the Kominka Movement, along with their aesthetic evolutions and audience responses; 3. the ideas and strategies of the Kominka Drama. The development of Taiwanese theater during these four years, as I find, was not in total darkness or stagnation, but underwent at one time or another disruption, fusion and growth. Under the general control of the colonial government, theatrical activities still retained certain degrees of liberty in terms of creativity and marketing. Their changes reflect not only the specific contents of the Kominka Movement, but also the cultural developments in Taiwan under the colonial modernization. They inspired the discussions in 1941 about where Taiwanese theater should go, which led to the revival of the New Theater Movement three years later, and their aesthetic influences extended further into the Taiwanese opera and the New Theater during the postwar period. "Dark" as it appears, this era carries its underestimated significance in the history of Taiwanese theater, and deserves to be reevaluated.