Having pulled out of the League of Nations following its condemnation of their invasion of Manchuria, the Japanese laid down two hulls for No. 1 battleship and No. 2 battleship. The managers of the Nagasaki shipyard were sworn to secrecy any violation of which was to be punished by whatever punishment the navy deemed appropriate according to the document they had to sign.
Each ship was huge, and the shipways and cranes had to be completely rebuilt to handle their enormous size and weight which dwarfed anything at sea. Carrying 18" guns they were 124 feet wide (to accommodate the tremendous recoil of the guns) some thirty feet wider than the previous records. and they had 40 centimeter (about 16 inches) thick hulls. Each ship would have both diesel and steam engines, diesel having been unreliable. The hulls were specially reinforced to fend off the new shells that they learned could still damage a vessel even in a near miss. They had to build a new freighter with an especially wide hull to transport the 18 inch-turrets to Nagasaki. They had never made rivets this big before. They needed 4-centimeter diameter (about 1.5 inches) rivets and because of the thickness of the hull had to be precisely made.
The book is as much about secrecy as building the ship with its myriad detail about specifications. The Japanese were obsessed with hiding the ship's construction. They built special hemp screens all around the building site, constructed a warehouse in front of the British consulate which had a view of the harbor, and arrested anyone who even looked at the buildings. The incident of the missing blueprint, which turned out to have been destroyed by a young draftsman hoping to work someplace else in the plant, resulted in the imprisonment and torture of several completely innocent designers before the discovered the culprit. All Chinese were deported and anyone protesting the deportations was placed under special watch. When the ship was finally launched, they organized am air raid drill to keep people in their homes, and when the ship caused a mini tidal wave that flooded several homes - -the water in the bay rose 50 centimeters just from the displacement of the huge ship -- police forbad them from leaving their flooded homes lest they see the size of the ship before it could be moved to another dock and again hidden from view.
All because they were afraid the United States might discover the size of the battleships, a size, as it turned out, that was totally irrelevant since the carriers came to dominate naval warfare. Indeed, their 18-inch guns could shoot over the horizon and dominate all other surface ships, but it was those little winged gnats with torpedoes that spelled its doom. Even the Japanese recognized the ultimate uselessness of these great ships and converted battleships 3 and 4 to aircraft carriers.
The desire for secrecy continued to the end. After its sinking, in order to prevent anyone from learning of the loss, the surviving sailors were stripped of their Musashi identity and assigned to some mythical unit. Many were transported back to Japan and were torpedoed again, rescued, reassigned to another ship and again torpedoed. About 146 made it to Corregidor -they were never allowed to leave the Philippines, again to prevent anyone learning of the disaster, where all but 29 were killed in the defense of Manila.
Marred by a couple of minor errors probably due to errors of translation along with a couple of "then's" where "than''s" were called for, it's a fascinating look at the creation and demise of the great battleships.