IV (海中4型（呂二六型）, Kaichū-yon-gata, Ro-26-class) Toku-Chū/Kaichū V (特中型/海中5型（呂二九型）, Toku-Chū-gata/Kaichū-go-gata, Ro-29-class) Kaichū VI (海中6型（呂三三型）, Kaichū-roku-gata...

classes: Type L1 (L1型（呂五十一型）, Ro-go-jū-ichi-gata, Ro-51-class) Type L2 (L2型（呂五十三型）, Ro-go-jū-san-gata, Ro-53-class) Type L3 (L3型（呂五十七型）, Ro-go-jū-shichi-gata...

The Type F submarines (F型潜水艦, F-gata Sensuikan) were medium Imperial Japanese Navy submarines in commission during the 1920s. They were Japan's first true...