In 1925, after years of piecemeal expansions, the Diet passed the Universal Suffrage Act. The act opened the franchise to all male residents of the inner territory who were at least 25 and had been at their place of residence for at least a year. In practice, these qualifications -- age, gender, length of residence -- disenfranchised the majority of the inner territory's residents. As the Asahi newspaper editorial board complained, "The question of universal suffrage has not been answered or solved by this action" (Asahi 1925, quoted in Lu 1996). Despite the title "universal," only about twenty percent of Japanese residents of the inner territory were eligible to vote. The numbers were even lower for Korean residents of Japan. Between 1928 and 1937, roughly ten percent of Korean residents were eligible (Matsuda 1995, 36-37). But, in theory, the Universal Suffrage Act represented a radical rethinking of the spatial formation of the Japanese Empire. The Universal Suffrage Act drew a stark core-periphery boundary between the inner territory and the colonies that had before operated at a the level of ethnicity rather than geography.
The move elicited the ire of Japanese residents of the colonies (Uchida 2011, 273; O'Dwyer 2015, 216-18). It also prompted Cai to seize this moment of substantive change in the empire's spatial formation to enroll Japanese residents of the metropole in the Taiwanese anti-colonial movement.