YOYA KAWAMURA (1739-LIFE-1991) sent photos and descriptions of two different mini-submarines of the I.J.N. during World War II. His uncle served aboard a two-man KOHYOTEKI, which was the fastest submarine in the world at that time - capable of UNDERWATER speeds of 20 knots!

KOHYOTEKI two-man submarines carried two torpedoes and were capable of 20 knots submerged. They were used in attacks against Pearl Harbor, Sydney, Diego Suarez (Madagascal) and Lunga (Guadalcanal). This type was carried aboard a large “I” boat and released a short distance from the target. The I.J.N. High Command claimed that one of these little boats sank the battleship USS ARIZONA which was incorrect. While this two-man submarine was not designed as a suicide weapon, the crew was rarely saved.

KAIRYU (Sea Dragon) was a winged submersible suicide craft with more than a half ton of high explosive in the bow. While this craft was never used in combat, a large number were deployed on the Japanese mainland against the possible ALLIED invasion.

Many thanks for the information, YOYA.