Entering the United States market is no longer a question of scale, but of design. The conclusion of this article is simple: Japanese and non‑US firms succeed in the US not by “localizing harder,” but by re-architecting decision rights, risk allocation, and partner incentives from day one. The US is the world’s largest consumer and capital market, yet it is structurally fragmented, regulatorily complex, and operationally unforgiving. This article breaks US market entry into concrete decision components—entry mode, governance, control, capital commitment, and organizational design—grounded in data and real cases. A key twist challenges the assumption that wholly owned subsidiaries are the safest path; in many sectors, asymmetric joint ventures and ecosystem partnerships outperform. Readers gain a practical framework to evaluate when, where, and how to enter the US—while avoiding the most common and expensive mistakes.