The Kosuga district was the one of the outer districts of Otosan Uchi, along the northern banks of the River of the Sun where it joined the Golden Sun Bay. It was an amalgam of two sub-districts, Kosuga and Yatoshin district. Most of Otosan Uchi's port trade occurred in the Kosuga district, and the area was well-maintained and highly populated. Even at night, heimin could be seen carrying torches leading workers to their jobs, and the area was considered to be middle-classed. There was also a small ronin population. It was also known as the South Dock district.