This chapter examines the diplomatic efforts surrounding the transmission of a letter from the Bogd Khan of Mongolia to the Emperor of Japan in 1914. The letter, facilitated by the Russian Foreign Ministry, was ultimately rejected by Japan due to concerns over its origins and implications for Japanese foreign policy. The correspondence between Russian and Japanese diplomats reveals a cautious approach by Japan, which sought to maintain amicable relations with Russia while avoiding entanglement in Mongolian affairs. Scholars such as J. Friters, F. Isono, T. Nakami, and Ts. Batbayar have analyzed this episode, highlighting the role of Kodama, an employee of the South Manchurian Railway, whose engagement with the Urga government influenced Mongolia’s outreach to Japan. The Russian government, wary of Mongolian ambitions for unification, also played a key role in discouraging direct relations between Mongolia and Japan. Archival documents from Russian and Japanese sources provide further insight into the political complexities of the period and Japan’s ambiguous stance toward Mongolia. The paper argues that Japan’s decision to return the letter was not simply a rejection but a strategic maneuver within the broader framework of Russo-Japanese agreements and regional diplomacy.