Has Korea ever established a decent anti-Japanese armed force in history?

Yes, but it is conceivable that the ability is limited.

19 10 After Japan forced North Korea and Japan to sign the Treaty of Japan-South Korea Merger (Japan-South Korea Merger), North Korea became a Japanese colony in disguise, and the Korean independence faction established the provisional government of the Republic of Korea in Shanghai. After Shanghai was captured by Japan, more than ten core members of the government in exile went into exile in Chongqing. During the period from War of Resistance against Japanese Aggression 1939 to 1945, the Provisional Government of the Republic of Korea established the Guangfu Army in Chongqing. Taking advantage of being familiar with Japanese, the Guangfu Army mainly engaged in writing slogans, broadcasting propaganda to the enemy, disintegrating the enemy, interrogating enemy prisoners, and deciphering enemy passwords. Starting from 1932, Kim Il Sung started anti-Japanese guerrilla activities in northeast China. Guerrillas led by North Korean producers are one of the most important anti-Japanese forces in North Korea. The troops led by Kim Il Sung captured Putianbao town in northern Korea in 1937, but were forced to quit the Soviet Union in 194 1.