The South Korean legal system is founded on a binary model of gender based on heterosexuality. It regulates the lives of lesbian, gay, bisexual, transgender, and intersex (LGBTI) people by enforcing laws that produce gender in accordance with this binary model. The family in Korean society is associated with the family headship system (hojuje)—which has simultaneously functioned both as a system of legal identification and as the mechanism directly responsible for the production of gendered kungmin or national subjects. As part of the family headship system, the gendered kungmin is classified as father or mother, wife or husband, and daughter or son, thereby reinforcing compulsory gender roles within the family. The Republic of Korea (ROK) military, too, is an important gender system fixated on binary gender classification, in that it targets all males as objects of conscription, at least in principle if not in actuality, and manages the male body through physical examination and discipline. Persons with nonconforming sexual orientation or gender identity who seek to live outside the prevailing gender system are deemed unfit and in violation of the heteronormative binary gender norms. This article problematizes the South Korean gender system as revealed in its interactions with LGBTI persons in three interlocking contexts: family, legal identity, and the military. By critically examining these modalities of the South Korean gender system, the author argues that the law renders LGBTI persons as unsuitable national subjects because they trouble the existing gender paradigm in significant ways.