Designed as a replacement for the D3A 'Val' dive bomber with long range and the speed of the A6M Zero fighter, the Yokosuka D4Y Suisei (Comet) suffered from development troubles and only entered service in quantity in 1944, too late to affect the outcome of the war (original service aircraft had been sunk at Midway with the Soryu). Their combat debut was during the Battle of the Philippine Sea but were ravaged by US fighters with hardly a success achieved, lack of carriers prompted most aircraft to subsequently fly from land bases where they were marginally successful, their most notable action being the sinking the USS Princeton during the Battle of Leyte Gulf. Like most dive bombers, the D4Y would have required air superiority (something that Japan sorely lacked in 1944) to be truly effective, this was unfortunate due to the superb characteristics of the aircraft which under different circumstances would have been a greater threat. Nevertheless many were used as kamikazes and some even as night fighters with obliquely-fixed cannon.

Based on the German He 118, the first D4Y was flown in December 1940 but flutter problems delayed service entry until two years later in the form of the the standard D4Y1 dive bomber and the D4Y1-C reconnaissance variant (these were some of the few Japanese aircraft with liquid-cooled engines). The D4Y2 followed in 1944 with Aichi Atsuta 32 engines but these were somewhat problematic and were subsituted for the Kinsei 62 in the D4Y3. Other variants include the single-seat D4Y4 designed exclusively for suicide missions and the dedicated D4Y2-S night fighter with 20-mm cannon fixed obliquely behind the rear cockpit.