The Nankai Maru, which is sailing through the South China Sea, is attacked by Kuro Kumo Maru, a member of the Black Moto Party, and Yori becomes a slave. Afterwards, the leader of the dark party, Arami Unemon, also attacks a Nanban ship, obtains the letter of appointment of the head of a trading post in Nagasaki, and disguises himself as Captain Kapitan to board Nagasaki. Arami's evil plan seemed to be a success, but Hakuba Douji, an ally of justice and a child of the sun appears, and the dark party is wiped out...