The Type F submarines were designed by the Italian firm Fiat-Laurenti and built under license by Kawasaki at Kobe, Japan.

[1] They were the Imperial Japanese Navy′s first true seagoing submarines,[1] and when the Japanese adopted a three-tiered classification system of its submarines as first-class (I), second-class or medium (Ro), and third-class (Ha) on 1 November 1924,[2] the Type F submarines were the earliest to receive the second-class classification,[1] as reflected in their low numbers in the Ro series,[1] and in fact they were the earliest Japanese submarine classified as anything higher than third-class.

[1] For surface running, the submarines were powered by two 1,300-brake-horsepower (969 kW) Fiat diesel engines, each driving one propeller shaft.

[1] When submerged each propeller was driven by a Savigliano 600-horsepower (447 kW) electric motor.

[1] On the surface, they had a range of 3,500 nautical miles (6,500 km; 4,000 mi) at 10 knots (19 km/h; 12 mph);[1] submerged, they had a range of 80 nmi (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph).

31 was attached to the Sasebo Naval District and assigned to Submarine Division 23.