Jeong Mong-ju was dispatched to Japan as an envoy in September 1377 to resolve the serious damage to Goryeo caused by Japanese pirates. Jeong Mong-ju stayed in Japan for about seven months, interacting with Kyushu Tandai Imagawa Sadayo and the Japanese, earnestly explaining the importance of understanding friendly relations and demanding that they prohibit treason. He successfully completed his mission, including repatriating hundreds of prisoners, and returned to Goryeo. It seems that he had emotional exchanges with the Japanese during his stay in Japan, and his activities were praised several times as an exemplary case of friendly relations by later Joseon Dynasty Diplomatic Missionaries. Moreover, the fact that Jeong Mong-ju had friendly relations with Japan was already known to Japanese intellectuals in the pre-modern era through examples such as the “Honcho Tsugang”, and Hayashi Razan and others asked about Jeong Mong-ju's death during their exchanges with the Joseon Dynasty Diplomatic Missionaries. As Japan entered the modern era, Jeong Mong-ju was described in numerous Japanese documents and came to be evaluated in more diverse aspects than in the pre-modern era. As a diplomat and an exchanger with Japan, he experienced not only academic exchanges with the Japanese, but also a deep sympathy for understanding each other’s customs, and through this, the Japanese praised him and evaluated him as a symbol of Korea-Japan harmony. As a Confucian scholar and scholar, he left behind outstanding achievements and was evaluated as the “best figure of Goryeo,” and his collected works, “Poeunjip”, are also highly regarded. As a loyal subject of Goryeo who met a tragic death, he aroused the sorrow of many Japanese people, and the Seonjuk Bridge where he died was visited by Japanese mourners, and legends about him were recorded in various Japanese documents. In this way, in modern Japan, Jeong Mong-ju was evaluated as a symbol of Korea-Japan reconciliation, a man of letters, and a loyal subject, and his name became widely known in Japanese society.
