Yokosuka B4Y1 Type 96 (“135”) Imperial Japanese Navy. The Yokosuka B4Y (Navy Type 96 Carrier Attack Bomber) was a carrier-borne torpedo bomber used by the Imperial Japanese Navy Air Service from 1936 to 1943. The B4Y replaced the Mitsubishi B2M2 and the Yokosuka B3Y, and was the last biplane bomber used operationally by the Imperial Japanese Navy. The Allied reporting name was "Jean". This aircraft was mistakenly identified by the British as the Nakajima Navy G-96. In 1932, the Imperial Japanese Navy issued a requirement for a new carrier-borne attack aircraft. Aichi, Mitsubishi and Nakajima responded to this requirement and each built a prototype. None of these aircraft were deemed satisfactory, and the service thus issued in 1934 a new requirement, 9-Shi, for a more capable aircraft to replace the obsolescent Yokosuka B3Y. The B4Y was designed by Sanae Kawasaki at the First Naval Air Technical Arsenal at Yokosuka. Regarded only as an interim type, the Navy wa...