The San Francisco Maru was a 385ft/117m, 5,831-ton Passenger-Cargo ship built in 1919 for Yamashita Kisen Kabushiki Kaisha as part of its fleet involved in world trade operations in minerals such as coal, bauxite, and phosphate for transportation to the Empire. The word ‘Maru’ designates a merchant vessel. Following requisition by the Japanese Navy, it was assigned to convey Japanese Navy Branch military cargoes between the Japanese homeland and the Inner South Seas. On May 4th 1943 Allied intelligence intercepted a damage report from the San Francisco Maru’s commander saying that she had received minor damage from attacking aircraft at Wewak, New Guinea. Following repairs, later prisoner interrogations revealed that she arrived at Truk Lagoon on February 5th 1944. Aerial photos show her lying at the 4th Fleet anchorage southeast of Dublon.