In 1935 a massive asteroid clashed into the sea of the coast of Hokkaido. A few months later nearby Japanese fishing boats spotted a small rocky island suddenly appeared to be floating above the sea level.
A team of Japanese naval scientists was sent to investigate the rock. It was discovered that the rock exhibits lighter than air property and is 100 times lighter than helium. With a good mixture of air it is possible to adjust the floatation height of the rock in the air.
With the war with the US imminent, the Imperial Japanese navy specifed a sky fortress to be laid down by adapting the old battleship Kongo to the “air rock”. It retained the old battleship’s massive 14 inches guns and was powered by 2 early modifieded and enlarged jet engines, a technology borrowed from their axis partner Germany. It was constructed in a secret base hidden in Mount Kongo in Osaka prefecture. It was until May 1945 that Kongo was first launched with many upgrades such as a hangar and launch deck for the new cherry blossom long-lance human piloted aerial torpedo.
By then the pacific war was at the door step of Japan. Super battleship Yamato was sunk and the Japanese war machine was on a brink of total destruction. I.J.N Air fortress Kongo was to be the triumph card to repel the invasion of Japan. It proved to be a devastating weapon. The allies has no answer to counter Kongo defensive measures. The thick rock formation is impervious against bomb attack and heavy losses were ininflicted on the planes sent to bring down the rock. Kongo has a smoke generator that provides an effective cloud screen to prevent conventional bombings. Its rock surface is able to absorb radar waves and rendered itself almost invisible to radar technology. With the command of the air, the sky fortress is able to re plunging shells from the sky at great distance.
With no war machine to match the might of Kongo. The allies may need to reinvent their doctrine to capture the Japanese home islands.