The Imperial Japanese Navy told Aichi in January 1940 to build a flying boat trainer. Morishige Mori designed the H9A1 between May and December 1940.
The H9A1 was of an all metal frame with allow, ply, and fabric coverings.
Crew and Students
There was room for three students in addition to the pilot, co-pilot, observer, flight engineer, and radio operator.
There were two 7.7 mm machine guns, one in each of the bow and dorsal positions for training. For depth charge training there was room for two.