The headquarters of the Murakami Kaizoku was a dense island chain called the Geiyo Islands. While the surface of the sea seems tranquil there, violent currents mercilessly assault any ship that attempts to traverse the narrow channels between them. It is one of the more difficult sea lanes to navigate, and has caused difficulties for mariners since ancient times. For this reason, the help of the Murakami Kaizoku, who had deep familiarity with these waters, was in demand, and they used their location to their advantage well to become the champions of the Seto Inland Sea.