Clear Sky Storm

The Aichi M6A Seiran (晴嵐, "Clear Sky Storm") was a submarine-launched attack floatplane designed for the Imperial Japanese Navy during World War II. It was intended to operate from I-400 class submarines whose original mission was to conduct aerial attacks against the United States.

From the late 1920s, the Imperial Japanese Navy had developed a doctrine of operating floatplanes from submarines to search for targets. In December 1941, Commander-in-Chief of the Japanese Combined Fleet, Admiral Isoroku Yamamoto, proposed constructing a large fleet of submarine aircraft carriers whose purpose was to mount aerial attacks against American coastal cities. The submarines would surface to launch their aircraft by catapult, submerge to avoid detection, then surface again to retrieve the aircrews who would ditch their planes nearby. By June 1942, the plan was to build a fleet of eighteen such subs. This was later cut to nine, then five and finally just three as Japan's wartime fortunes declined.

When the force was finally ready to set off on their mission against Panama, Japan's increasingly desperate situation led to a change in plan, with the target for the attack, called Operation Hikari (Splendour), being switched to the American base at Ulithi Atoll where forces, were massing in preparation for attacks on the Japanese Home Islands. On 16 August, the flagship I-401 received a radio message from headquarters, informing them of Japan's surrender and ordering them to return to Japan. All six Seirans on board the two submarines, having been disguised for the operation as American planes in violation of the laws of war, were catapulted into the sea with their wings and stabilizers folded or pushed overboard to prevent capture
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Text-Source: Wikipedia