Sin-ai Maru was a transport of the Imperial Japanese Navy, an AP whose wartime place was in the Bismarck Sea convoy.
She was with that convoy when it met the Battle of the Bismarck Sea. The battle is dated 2 March 1943, and she is marked sunk in it.
Her fate is sunk by Allied aircraft across 2 and 3 March 1943, the two days given for the loss in the Bismarck Sea.
On 3 March a bomb is recorded as the blow that sank her. Allied aircraft delivered it. The aircraft are not identified, and the sinking is not credited to one plane.
The bomb ended her. Sin-ai Maru went down as a convoy transport in the Battle of the Bismarck Sea, lost to Allied aircraft on those March days in 1943.