One of Yi's most ambitious works is "Frontier Between Two Empires" known as "Border", an epic novel in 12 Volumes. The title symbolizes the United States and the former Soviet Union. It is essentially a sequel to "Age of Heroes" in describing the lives of a family left behind in South Korea after their father defaults to North Korea. It characterizes the hardships brought about by the Korean War and the imprint of superpower rivalry. In a critique of his own work, he stated the premise of the book was that in order to secure the South Korean border the United States imposed Western capitalism and the South Korean government used absolute authority to enforce it. "As a result, South Korea becomes a society where the only 'freedom' allowed is the pursuit of money; and the dreaming of a better society or individual life is banned. Thus, various entities, which want to be freed from this evil axiom, spring forth. However, their good intentions are soon distorted. They turn antagonistic toward those who do not have faith in their good intentions, while demanding absolute obedience from those who believe in their good intentions."