The Cruiser submarine Type-A was a class of submarine in the Imperial Japanese Navy (IJN), which served during the Second World War. The Type-A submarines were built to take a role of the command ships for submarine squadrons. For this reason they had equipment for a headquarters, better radio facilities and a floatplane.

The Junsen type submarine was a ship class of submarines of the Imperial Japanese Navy (IJN). There were four submarine designs of the Junsen type: J1, a modified J1, J2 and the J3.