The Mitsubishi F1M was designed to be a catapult launched observation floatplane. It was to meet a late 1934 Imperial Japanese Navy specification for a replacement for the Nakajima E8N1. Aichi and Kawanishi also tried to meet the requirements. Kawanishi withdrew and Aichi's was inadequate.
The Mitsubishi design team was lead by Joji Hattori.
A couple problems the F1M had was it would often porpoise in water and directional stability in flight.
The F1M was of all metal construction with the control surfaces being covered by fabric.
There was a main, central, float, and two stabilizers attached to the lower wing.
The F1M2 was a major redesign that appeared in 1939.