All boats were built in the Mitsubishi Heavy Industries-Kobe Shipyard by the contract with Vickers.

The changes were: The Type L3 is a license production model of the British L class submarine Group 2.

The Type L4 is a license production model of the British L class submarine Group 3.

The IJN was satisfied with them and stopped the development of Kaichū type submarines for a long time.

Later the IJN was not able to regain the technical delay in development of the medium-sized submarines until the end of the Pacific War.