Magane Maru was laid down on 14 December 1939 at the shipyard of Harima Zosensho at the behest of shipping company, Nihon Kaiun.[2][3] She was launched on 15 June 1940 and completed 5 August 1940.[3] On 5 September 1941, she was requisitioned by the Imperial Japanese Navy and converted to an auxiliary minelayer/gunboat under Reserve Lieutenant Maniwa Kenji (間庭建爾).[3] Armaments mounted were 1 x 8 cm/40 3rd Year Type naval gun, 1 twin Type 93 machinegun (jp) (based on the Hotchkiss M1929 machine gun), 1 Type 3 heavy machine gun, and 120 mines.[2] In December 1941, she was assigned to the 7th Base Force, Gunboat Division 10 of the 5th Fleet under Lieutenant Commandeer Sasaki Heiji (佐々木丙二)(jp).[3] The 7th Base Force was based in Ominato.[3] On 10 April 1942, she was detached from Gunboat Division 10[3] and attached to the Adak-Attu invasion force under Rear Admiral Sentarō Ōmori during the Aleutian Islands campaign.[4][5] On 25 September 1942, she was reassigned to the Yokosuka Naval District.[3] On 25 May 1943, Sasaki was replaced by Reserve Lieutenant Yamazaki Kiyoichi (山嵜來代一).[3] On 18 September 1943, Yamazaki was replaced by Reserve Lieutenant Shigematsu Yoshioka (吉岡茂松).[3]
^United States Strategic Bombing Survey (1946). The Campaigns of the Pacific War. U.S. Strategic Bombing Survey (Pacific) Naval Analysis Division, 1946. p. 99.