The B7A was designed in response to a 1941 requirement issued by the Imperial Japanese Navy for a carrier attack bomber that would replace both the Nakajima B6N Tenzan torpedo plane and the Yokosuka D4Y Suisei dive bomber in IJN service. Given the codename "Grace" by the Allies, it first flew as a prototype in May 1942, but problems with the delivery of the engines meant that it was not produced in numbers until 1944when it was too late to affect the outcome of the war. There were no aircraft carriers left for it to fly from, and only 105 aircraft were produced.
The powerplant was a 1,360 kW (1,825 hp) Nakajima NK9C Homare 12 18-cylinder two-row radial engine, and the aircraft featured a "bent" wing - an inverted gull wing somewhat reminiscent of the F4U Corsair - to give clearance for the propeller without requiring the use of long undercarriage legs.
The B7A had a weight-carrying capacity resulting in a weapons load no greater than its predecessors; the presence of an internal bomb bay with two high-load-capability attachment points allowed the aircraft to carry two 250 kg (550 lb) bombs. Despite its weight and size, it displayed fighter-like handling and performance, besting the version of the A6M Zero in service at the time. Fast and highly maneuverable, had it been produced earlier and in greater numbers, it would have proved a considerable adversary to the United States Navy's fighters.
                                                                                                                                    -- Wikipedia