'U' (i) was the Japanese maritime undertaking to deliver Lieutenant General Renya Mutaguchi’s 18th Division, Lieutenant General Masao Watanabe’s 56th Division and a number of other units to newly captured Rangoon, the capital of Burma (25 March/14 April 1942).
For this undertaking, the Imperial Japanese navy’s Transport Unit No. 3 departed Singapore with 32 ships including the 9,492-ton Teikai Maru, 9,256-ton Anyo Maru, 5,829-ton England Maru, 8,613-ton Ginyo Maru, 5,724-ton Kuwayama Maru, 2,910-ton Kochi Maru, 3,377-ton Kenkoku Maru, 4,013-ton Samarang Maru, 4,645-ton Suez Maru, 2,478-ton Taikai Maru, 5,477-ton Tazan Maru, 5,271-ton Hamburg Maru, 6,446-ton Buyo Maru, 5,652-ton Havre Maru, 5,858-ton Brazil Maru, 5,214-ton Penang Maru, 8,359-ton Hokuriku Maru, 6,570-ton Montreal Maru, 1,852-ton Yawata Maru and 5,274-ton Yoneyama Maru.
While the main strength of the two divisions travelled from Singapore, some other of their elements made their passage to Rangoon in multi-ship convoys from Japan and Penang in western Malaya. The latter convoy included the 6,359-ton transport Aobasan Maru, was supported on its passage from Malaya by the escort vessel Shimushu, and was preceded into Rangoon harbour by the minesweepers W-1 and W-4. Another convoy delivered further reinforcement in the form of the 1st Tank Regiment, 14th Tank Regiment, two regiments of heavy field artillery, two independent engineer regiments and a number of supporting anti-tank, anti-aircraft, signals and line of communication units.
After being delivered to Rangoon, the divisions and units moved to join the 'B' (iii) operation of Lieutenant General Shojiro Iida’s 15th Army (Lieutenant General Shozo Sakurai’s 33rd Division and Lieutenant General Hiroshi Takeuchi’s 55th Division) to take central and northern Burma from the British, who by this time had considerable Chinese support.