In 1943 she survived hitting a mine, and she aided the cruiser Aoba after a USAAF air raid crippled her.

Uraga went on to build numerous other ships with the same propulsion system, including at least ten of the same class as Rakuto Maru.

[13] At the same time as White Pioneer was being built, Uraga applied similar principles to Rakuto Maru and her two sisters.

From 1937 onward, Uraga built several more cargo ships to the same design as Rakuto Maru, and with the same combination of compound engine; exhaust turbine; and reduction gearing.

The Second Sino-Japanese War began that July, and Rakuto Maru remained in Army service until early 1939, when she was returned to her owners.

On 19 November she arrived at Osaka Iron Works at Innoshima, Hiroshima, to be converted into an auxiliary transport.

She left Kure in convoy with another auxiliary transport, Kunitsu Maru, escorted by the destroyer Wakatake.

Later she moved to Daliao, about 8 nautical miles (15 km) southwest of Davao, where she joined the fleet assembling to invade the island of Tarakan in the Dutch East Indies.

In the first week of March, Rakuto Maru supplied Imperial Japanese Navy Air Service units in southern Bali.

[2] From Bali, Rakuto Maru sailed to Kupang in West Timor, where on 27 March she was slightly damaged in an Allied air raid.

On 10 April, while she was at sea between Ambon and Takao, Rakuto Maru was transferred from the Navy Air Service to the Kure Naval District.

After Takao, Rakuto Maru called at Osaka; Seito (now Qingdao) in China); Fushiki in Toyama Prefecture; and Moji.

She called at Kirun (now Keelung) in Taiwan; Manila; Davao; Zamboanga; Isabela, Basilan; Mako (now Magong), in the Penghu archipelago; Osaka; and Moji; and on 31 July arrived back at Kure, where she spent a fortnight in port.

From 27 January to 1 February she was in Haiphong in Indochina, where she loaded cargo including 2,117 tons of zinc ore. From 4 to 7 February she was in Hong Kong, where she loaded cargo including 1,350 cubic metres (48,000 cu ft) of cotton, and embarked 30 passengers.

She called at Kirun; and from 9 to 15 March was in Takao, where she loaded 3,020 cubic metres (107,000 cu ft) of supplies and 92 tons of other cargo.

From 22 to 24 March she was in Palau, where she discharged 85 tons of rice, and loaded one landing craft and 19 cubic metres (670 cu ft) of building materials.

The next day, the US 43rd Air Mobility Operations Group attacked Japanese naval ships at anchor off Kavieng, New Ireland.

Rakuto Maru came alongside Aoba, transferred 55 tons of medical supplies to the cruiser, and embarked 62 passengers.

She called at Komatsushima, Tokushima, and on 13 June arrived at Kure, where she unloaded scrap iron, and underwent general repairs.

[2] After repairs, Rakuto Maru loaded bombs, postal parcels, and general cargo, and on 19 July she left Kure.

She called at Cebu; and from 16 to 28 August was in Balikpapan, where she unloaded 500 tons of iron pipes and 190 cubic metres (6,700 cu ft) of rations, and loaded postal parcels.

She called at Makassar, and from 8 to 14 September was in Ambon, where she unloaded 630 cubic metres (22,000 cu ft) of bombs, aircraft parts, and aircraft weapons; 250 cubic metres (8,800 cu ft) of provisions; and two Daihatsu landing craft.

[2] From 17 to 18 September, Rakuto Maru was in Kendari, Sulawesi, where she unloaded 300 cubic metres (11,000 cu ft) of bombs, aircraft parts, and aircraft weapons; and 50 cubic metres (1,800 cu ft) of other weapons.

From 14 to 18 October she was in Makassar, where she unloaded hemp fibre and trucks, and loaded 2,000 tons of nickel ore. On 19 October she reached Pomalaa in Southeast Sulawesi, where she disemblarked 242 troops and discharged her nickel ore, and diesel engines for trucks.

It exploded on her starboard side amidships, flooding her engine room and causing extensive damage.

She remained afloat; received emergency repairs; and the salvage tug Akitsu Maru towed her to the harbour pier.

From 23 to 29 January she sailed to Saint-Jacques (now Vũng Tàu) and Saigon (now Ho Chi Minh City).

The convoy left Saint-Jacques on 1 February, and called at Yulin, where the auxiliary gunboat Huashan Maru relieved Karukaya as its escort.

On 10 February, the submarine USS Spearfish attacked the convoy, damaging the naval auxiliary transport Tatsuawa Maru with one torpedo.

she called at Wakamatsu; Yoshiura; Hirohata in Himeji; Osaka; Moji; Kobe; Wakayama; Aga-Machi; Komatsushima; Etajima; Yawata; Tokuyama; and Chinnampo in Chōsen (now Nampo in North Korea).