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.
There was a main, central, float, and two stabilizers attached to the lower wing.
The F1M2 was a major redesign that appeared in 1939.