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