After the Japanese Invasion of Korea in 1592, Iljimae, a master of the interlaced sword method, heads to Japan to find the national treasure, the Cheonryongsword, which was robbed by the Japanese pirate Kuroda. Around this time, there were two more men looking for Kuroda, one of them was Ma-cheol, a one-armed swordsman who lost his left arm due to Kuroda's trick, and the other was Kuroda's henchman Okamodo, who lost his newlywed wife and even lost his own eyes. This is Yoshiyama, the swordsman who lost his mind. At first, the three knights, who met by chance, were wary of each other for their own goals, but were captured by Kuroda's persistent pursuit. In the end, after a bloody fight, they succeed in revenge, and Iljimae returns home with the recovered Cheonryongsword.