The I-400 belonged to a class of Japanese submarines that was the largest in the world until the development of nuclear ballistic missile subs during the 1960s. They still stand as the largest non-nuke subs ever built. They were designed as submarine aircraft carriers, capable of carrying 3 Aichi M6A Seiran seaplanes in a main deck hangar, launching aircraft from a catapult on the front main deck. They carried offensive and defensive weapons in the form of torpedoes, anti-aircraft guns, and a large deck cannon. Of the 18 originally planned, only 3 were built: the I-400, the I-401, and the I-402.

Aoshima's waterline-only I-400 kit is beautifully molded in gray plastic and comes with a full complement of aircraft (some unused). A great addition to any 1/700 collection of military vessels.