King of Japan (Nihon Kokuo) (日本国王)

The king of Japan was a title of the ruler of Japan, which was used mainly by the head of the military government internationally during the medieval and early-modern times. It had come to be used as the diplomatic title of the Muromachi shogun since Yoshimitsu ASHIKAGA, the third shogun of Muromachi shogunate government, was appointed king of Japan under a seal of investiture of a title of 'Nihon-kokuo Gen Dogi' by the emperor of the Ming dynasty. At present, this term sometimes refers to the emperor of Japan (tenno) in the Korean Peninsula.

Before Yoshimitsu ASHIKAGA

In Chinese historical documents, the ruler of Japan was called 'the king of Wo' but in the Tang dynasty era, the term 'the king of Japan' (Nihon-kokuo) came into use. The phrase, 'Edicts for the King of Japan,' is seen in the "The Collection of Qu Jiang Zhang, Chancellor of Tang dynasty" (唐丞相曲江張先生文集). In addition, the sentense which read, 'in 1266 a diplomatic message of Kublai Khan, the emperor of the Yuan dynasty, was sent to 'the king of Japan' in 1266,' is seen in "Chapter of Japan" in the "History of Yuan Dynasty (Yuan-shi)." However, in both cases, "the king of Japan" referred to the emperor of Japan. In the period of the Northern and Southern Courts (Japan), Imperial Prince Kanenaga was given the title of the king of Japan under the name of 'Ryokai' by the Ming dynasty on the condition that he crack down on the Japanese pirates.
After Imperial Prince Kanenaga fell from power, there occurred an abnormal situation in which the shogunate government and the feudal lords in Kyushu traded with the Ming under the name of 'Ryokai, the king of Japan.'

Yoshimitsu and the king of Japan under the tributary system

Yoshimitsu ASHIKAGA sent an envoy to the Ming several times, in hopes of monopolizing the trade between Japan and the Ming. The Ming Dynasty also needed to have relations with the ruler of Japan, who was able to crack down on Japanese pirates, but they rejected the offer of trade with regard to the domestic opinion for the restoration of Confucianism, on the grounds that the Ashikaga clan was not the ruler of Japan but only a 'shogun,' or the vassal of the party of Jimyoin, who was considered by the Ming Dynasty as the name of the political opponent of 'Ryokai' (Imperial Prince Kanenaga) over the succession of the imperial throne. In 1380 Hu Weiyong, the Left Chancellor of the Ming Dynasty, tried to communicate secretly with Yoshimitsu, who was then in the Buddhist priesthood, and Yoshimitsu intended to begin trade without using his position as vassal of the emperor.
As a result, an envoy, who was dispatched in 1401 with the letter of 'Nihon Junsango Dogi,' accomplished the object and returned to Japan with a Ming envoy, who bore a letter of the Jianwen Emperor (period of reign: 1398 -1402) addressed to 'Nihon-kokuo Gen Dogi.'
It was said that Yoshimitsu courteously met the Ming envoy at Kitayama villa, and received the letter on bended knee.

While the Ming envoy was in Japan, the Emperor Yongle (period of reign: 1402-1424) ascended the throne in the wake of the Jingnan Incident (1399-1402). Yoshimitsu sent a letter to Emperor Yongle as well. The Emperor Yongle, who was accused of being a usurper soon after his ascension, welcomed the envoy from the 'outer barbarians' as an opportunity to prove his virtues, and gave Yoshimitsu the seal of 'the king of Japan' (Nihon-kokuo no in) and a tally (a certificate to show that the ship was lawfully registered by the Ming), which was necessary for trading.

In this way, Yoshimitsu obtained the title of 'the king of Japan,' and internationally acknowledged as a king who served the Chinese emperor. As a result, the Ashikaga clan held the initiative in the tally trade with China.

After Yoshimitsu

Yoshimochi ASHIKAGA, who became the fourth shogun after Yoshimitsu's death, broke off relations with Ming, but the sixth shogun Yoshinori ASHIKAGA resumed diplomatic relations. The title of the king was also revived.
In association with the above, letters from Korea called the shogun the king of Japan, while the Japanese side used the title of 'Somebody of the Minamoto clan, the king of Japan.'

During the peace negotiation process of Japan's first invasion of Korea in the Azuchi-Momoyama period, Emperor Wanli of the Ming sent a letter to Hideyoshi TOYOTOMI. In this letter was a sentence which read, 'I hereby appoint you the king of Japan,' but Hideyoshi refused the investiture by the Chinese court and started the Japan's second invasion of Korea. A story has been handed down that Hideyoshi was so infuriated that he tore the letter and threw it away, but this a fiction created later. In fact, the letter was kept by Yoshiharu HORIO, who received it from Hideyoshi, and is currently in the possession of the Osaka Museum of History as important cultural property (the official letter to Hideyoshi TOYOTOMI from the King of Ming, 綾本墨書 明王贈豊太閤冊封文).

Hidetada TOKUGAWA, the second shogun of Edo shogunate government, intended to resume diplomatic relations with the Yi dynasty of Korea, and ordered the So clan of Tsushima domain to negotiate. The So clan falsified a sovereign's message, using the title of 'the king of Japan' for the shogun. However, this falsification was revealed in 1633 (the Yanagawa Incident), and thereafter the shogunate government used the title of 'the Tycoon of Japan' (Nihonkoku Taikun) for the shogun.
The title of 'the king of Japan' was temporarily used in the era of Ieyoshi TOKUGAWA according to a proposal by Hakuseki ARAI, but Yoshimune TOKUGAWA again switched to 'Tycoon,' and all successive shoguns used the title of 'Tycoon.'

After the Meiji period, when the emperor of Japan became the head of state, he began to use the title of 'the emperor of Japan' or 'Nihonkoku Tenno' in foreign affairs as well, and the title of 'the king of Japan' fell into obscurity.

The title of Tenno in the Korean Peninsula

On the Korean Peninsula, people have traditionally admired the person who ruled Chugen (China) as emperor, and considered only that person qualified to use the term '皇' (emperor). Therefore, they didn't allow their own king or the kings of neighboring countries to use the character '皇' on the grounds that it went against reason, and they called the emperor of Japan 'the king of Japan' or '일본_천황' (Ilbon Chonhwang). The situation continues even today, and opinions in the world of mass media are split as to which should be used in situations which are not public occasions, 'the king of Japan' (日王) or 'the emperor of Japan' (天皇), although most of the media uses 'the kinf of Japan' (日王). In connection with the above, some people point out the existence of Petit Sinocentrism in Korea.