[3][4] She served as a passenger ship for Osaka Shosen travelling from Kobe to New York via the Panama Canal and in 1938, further onward to Europe.

On 10 November 1941, she was designated an auxiliary transport and assigned to the Yokosuka Naval District under Captain Yamamura Minoru (山村實).

[3] On 13 December 1941, the convoy left Cam Ranh Bay, Indochina (Mitakesan Maru is later detached to deliver supplies to the Philippines).

On 15 December 1941, the transports arrived and disembarked their troops unopposed at Seria, Miri, and Lutong, successfully occupying the airfields and oil wells.

[3] On 26 December 1941, Dutch Army Martin B-10 bombers from Samarinda, Borneo bomb and sink the minesweeper W-6 and the transport/collier Unyo Maru No.

[3] In August 1944, she was part of the ill-fated fast convoy HI-71 under Rear Admiral Kajioka Sadamichi which had left Mako, Taiwan for Manila in a typhoon to deliver much-needed troops and supplies for the defense of the Philippines.

In the morning on 18 August 1944, the convoy is attacked by the American submarine USS Redfish which torpedoed and damaged the oiler Eiyo Maru (which is forced to return to Takao escorted by destroyers Asakaze and Yunagi).

American submarines USS Bluefish and USS Spadefish join in the attack with Bluefish sinking the fleet oiler Hayasui and the oiler Teiyō Maru; and Spadefish sinking the landing craft depot ship Tamatsu Maru (killing 4,890 including 4,755 troops).

[3] On 21 September 1944, Hokkai Maru departed Surabaya, Java escorted by gunboat Nankai (the ex-Dutch Regulus).

On 23 September 1944, Hokkai Maru and Nankai struck mines 15 miles west of Sebuku Island leaving both ships crippled.