This article suggests that Chosŏn government officials did not strictly adhere to the tributary system model of international relations in their dealings with Japanese in the fifteenth and sixteenth centuries. Officials borrowed from Chinese example and from domestic policy in designing Japanese access control policies that responded flexibly to political conditions in Japan. The munin access permits issued by the Tsushima shugo were perhaps the most important feature of these policies. But treatment of Tsushima and the Tsushima shugo by Korean officials made ambiguous the identities not only of Tsushima and the Tsushima shugo, but also the administrative boundaries of Chosŏn and Japan. These negotiable ambiguities raise questions of how to conceptualize relations between Koreans and Japanese in the fifteenth and sixteenth centuries.