The movie begins with an intro featuring dark atmospheric music, showing Wakisaka Yasuharu sending a red-lettered letter to Toyotomi Hideyoshi. It's July 1592, the lunar calendar, during the day at Busan Port, within the Japanese camp. Wakisaka Yasuharu appears with his subordinates. Around him, Korean prisoners are carrying goods, and Infiltrator Im Jun-young spills something in front of Wakisaka, who is passing by. Sahae tries to attack Im Jun-young immediately, but Watanabe Shichemon intervenes. Wakisaka continues to the barracks, where soldiers are hastily filling the boat. Sahae, surviving against the odds, reports the situation of the defeat to the defeated commander. He listens to the story of the turtle ship from Jangsu. When Sahae expresses fear of the turtle ship, calling it an underwater monster 'Bokkaisen,' Watanabe Shichemon cannot hide his fear. Sahae leaves, leaving behind words that fear is a contagious disease. Wakisaka Sahae and Manabe Samanojo draw their swords and slaughter the defeated soldiers.
Later, Wakisaka heads to the harbor with Watanabe. The flagship, Antaekseon's right side, has a huge hole, and Wakisaka mutters, 'A collision?' Watanabe tells Wakisaka that they brought it from the South China Sea, drifting. Wakisaka turns his head and discovers something stuck in the torn wooden pillar, pulling it out. It's a palm-sized fang, and this time, Wakisaka notices two more holes in the front left side of Antaekseon's hull. Looking at the giant hole again, as the sound of a ship splitting the sea grows louder, the dragon's head of the turtle ship emerges, smashing Antaekseon's right side."
