It had elliptical wings and great care had been taken to reduce drag, with the number of interplane struts and bracing wires minimised.

The wings were redesigned, with straight tapered leading and trailing edges and rigged with greater dihedral, and the vertical fin and rudder were enlarged.

The aircraft's floats were enlarged to increase buoyancy, and the Hikari engine was replaced by a 652 kilowatts (875 hp) Mitsubishi Zuisei 14-cylinder radial, giving better forward visibility.

The F1M was armed with a maximum of three 7.7 mm (.303 in) machine guns (two fixed forward-firing and one flexible rear-firing) with provision for two 60 kg (132 lb) bombs.

The "Pete" took on a number of local roles including convoy escort, bomber, anti-submarine, maritime patrol, rescue, transport, and anti-shipping strike; for example sinking Motor Torpedo Boat PT-34 on 9 April 1942.