Beginning in the first decade of the seventeenth century, Tokugawa Ieyasu, the effective ruler of Japan, sent dozens of letters to Cochinchina, Cambodia, Patani, the Philippines, and other states and colonies scattered across Southeast Asia. The dispatch of these documents marked a significant shift in Japanese diplomatic patterns. For the first time, Japan broke decisively from the confines of East Asia to connect with wider networks of trade and diplomacy. If the fact that such documents could be sent in the first place reveals new possibilities for engagement, their content highlights some of the problems created by the expansion of maritime trade routes in this period. Dispatched in response to a string of incidents in ports across the region, these letters provide clear evidence of the frequent violence that accompanied the Japanese push into Southeast Asia. In their willingness to shift easily between trade and violence, Japanese merchants bear a striking resemblance to their European rivals who appeared in the region at roughly the same time, and the last section of this article focuses on what these letters can tell us both about the similarities but also the key differences between these groups. In particular, it argues that these documents reveal a divergent attitude toward the relationship between state and subject that accounts in part for the relative success that Europeans enjoyed in early modern Asia.