Globalization processes have formed a triad of economic and trade systems in terms of GDP and trade volume. These are the European Union (EU), North America Free Trade Association (NAFTA), and Northeast Asia, the major actors in the global economic system and trade since 1990s. However, the global financial crisis in 2008 created a new global economic order and governance that consisted of existing global economic power such as the G7 as well as new emerging economic powers, such as G20 and BRICS. Under such rapidly changing global economic conditions, global trade has contributed to rapid economic growth in the world in the last half-century. Regarding FTAs, the European Union (EU) is the frontrunner and has developed the most advanced system for regional economic integration. The EU’s single market provides several implications for Northeast Asian countries trying to build their own regional bilateral and multilateral FTAs and participate in different mega-FTAs such as RCEP and TPP. As a result, their economic interests are rather divided deeply and related to political and security issues in the context of Northeast Asia. Therefore, it is more difficult for Northeast Asian countries to economically integrate in a way that is comparable with the EU. This paper addresses a regional FTA between South Korea, China, and Japan that could be a starting point for their formal economic integration and create a reliable platform to strengthen their trade, boosting further economic growth. It also asks which of the three nations’ economic interests are served by participating in mega FTAs such as RCEP and TPP. Finally, it analyses the best scenario for participating in the multilateral FTA and mega FTAs for each nation.