Japan’s agriculture has been inward oriented, protected by trade barriers from foreign competition. Even though the share of Japan’s food consumption provided by Japanese production has gradually fallen, Japan’s farm sector remains the second-largest among the countries negotiating the Trans-Pacific Partnership (TPP). Japan’s food industry is increasingly integrated with TPP economies, although the TPP share of Japan’s agricultural imports has fallen over time. The proposed TPP agreement would lead to more agricultural exports to Japan from TPP partners, likely dominating the total agricultural trade impact of such an agreement. Despite potentially large import increases, especially in the rice, beef, and dairy sectors, the proposed agreement would only marginally reduce Japan’s output. Intrinsic strengths of Japanese agricultural production and constraints to the growth of supply in the rest of the TPP countries may limit the impact of the agreement on Japan’s agriculture. Nevertheless, U.S. exports would be well positioned to meet Japan’s new import demand.