
1.History reference
(1) overview
The two Japanese invasions of Korea took place from 1592 to 1598. Toyotomi Hideyoshi led the newly unified Japan into the first invasion (1592–1596) with the professed goal of conquering Joseon Dynasty Korea, the Jurchens, and eventually Ming Dynasty China,and the European Merchants. The second invasion (1597–1598) was aimed as a retaliatory offensive against Joseon Dynasty Korea and Ming Dynasty China as its ally. The invasions are also known as Hideyoshi's invasions of Korea, the Seven Year War (in reference to its span), the Imjin Waeran ,in reference to the "Imjin year of the sexagenary cycle in China, and Bunroku Keichō no eki

(2)Troop strength of Japan
Hideyoshi mobilized his army at the Nagoya Castle on Kyūshū (present-day Karatsu), newly built for the sole purpose of housing the invasion forces and the reserves. The first invasion consisted of nine divisions totaling 158,800 men, of which the last two of 21,500 were stationed as reserves in Tsushima and Iki respectively.
On the other hand, Joseon maintained only a few military units with no field army, and its defense depended heavily on the mobilization of the citizen soldiers in case of emergency. During the first invasion, Joseon deployed a total of 84,500 regular troops throughout, assisted by 22,000 non-regular volunteers. Aid from the Chinese during the war could not have made up for the difference in numbers since they never maintained more than 60,000 troops in Korea at any point of the war, while the Japanese used a total of 500,000 troops throughout the entire war
(3)The troops of Korea
Until the 16th, Korea has lasted long time peaceful time,so the army are weak compared to the Japanese warriors ,the armor of the general and elite troops are similer to Ming dynasity,and soldiers's equipment are poor .
But In response to the threats of wako from Japan, the Koreans developed a powerful navy, constructed a thorough defense line of fortresses along the Tumen River, and took control of the island of Tsushima. This defensive stance within an environment of relative peace pushed the Koreans to depend on a heavy artillery of fortresses and warships. With the transmission of gunpowder and firearmstechnology from China during the Goryeo Dynasty, Korea improved upon the original Chinese designs of firearms and developed advanced cannon which were used with great efficiency at sea. Even though China was the main source of new military technologies in Asia, Korea excelled in both cannon manufacturing and shipbuilding in this age.
here are some pictures of Korean army
(4)the Ming Empire
Ming Empire may be the most powerful country in the world at that time,the amount of Ming's army usually is usually beyond one million.
Ming military institutions were largely responsible for the success of Ming's armies. The early Ming's military was organized by the Wei-suo system, which split the army up into numerous "Wei" or commands throughout the Ming frontiers. Each wei was to be self-sufficient in agriculture, with the troops stationed there farming as well as training. This system also forced soldiers to serve hereditarily in the army; although effective in initially taking control of the empire, this military system proved unviable in the long run and collapsed in the 1430s, with Ming reverted to a professional volunteer army similar to Tang, Song and Later Han.
Ming demonstrated massive use of rocket-propelled arrows, notably during the Siege of Pyongyang in January 1593. During siege actions, Chinese deployed rattan shields and iron pavises (large shields), reputed to be musket-proof.
here are some pictures of Ming's Army